A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention

Abstract

Objective:

People experiencing severe mental illness report higher rates of tobacco smoking than the general population, while rates of quitting and sustaining abstinence are considerably lower. This systematic review aimed to identify factors associated with sustained abstinence in people experiencing severe mental illness following a smoking intervention.

Method:

Searches were conducted in PubMed, PsycInfo, Scopus, Embase, Emcare, CINAHL and Cochrane Library from the inception of the e-databases until June 2022. Selection criteria included randomised and non-randomised studies of smoking cessation interventions in which most of the participants were experiencing severe mental illness, and reported a follow-up of 3 months or longer. From an initial 1498 unique retrieved records, 26 references were included detailing 17 smoking cessation intervention studies and 3 relapse prevention intervention studies. Risk of bias was assessed using the RoB2 tool for randomised study designs and the ROBINS-I tool for non-randomised designs.

Results:

Participation in smoking interventions was associated with higher odds of abstinence in the medium-term, but not long-term follow-ups. There was insufficient evidence that any other factors impact sustained abstinence. Most studies were considered to have some risk of bias, largely due to insufficient availability of analysis plans.

Conclusion:

Despite an abundance of studies investigating smoking cessation in smokers experiencing severe mental illness, there is limited knowledge on the factors associated with staying quit. The inclusion of people experiencing severe mental illness in large-scale randomised control trials, in which predictors of sustained abstinence are measured in the medium and long term are needed to address this important question.

Keywords

Psychosis schizophrenia severe mental illness smoking cessation smoking abstinence

Introduction

People experiencing severe mental illness (SMI), such as schizophrenia or bipolar disorder, face a reduced life expectancy of approximately 10–15 years compared to the general population (Hjorthøj et al., 2017). This is largely explained by cardiometabolic and respiratory diseases to which smoking is a significant contributor (Brown et al., 2010). Around two-thirds of people experiencing SMI in high-income countries smoke tobacco, a rate much higher than the general population (Dickerson et al., 2018; Lawrence et al., 2009). While smoking rates in high-income countries internationally have declined over recent years in the general population, the reduction in smoking rates has been much slower in people experiencing SMI (Greenhalgh et al., 2022). People experiencing SMI smoke more heavily, consume more nicotine from each cigarette and report greater nicotine dependence (Bowden et al., 2011; McClave et al., 2010; Williams et al., 2005).

Many people experiencing SMI who smoke are motivated to quit and willing to seek quit support (Aschbrenner et al., 2015; Lappin et al., 2018). Cessation attempts are less likely to be successful, however, and relapse rates are higher for people experiencing SMI (Evins et al., 2014; McClave et al., 2010). Why this is the case is not well understood. It may in part be due to the greater barriers in accessing appropriate interventions faced by people experiencing SMI (Lum et al., 2018). Some of these barriers arise from the design and effectiveness of smoking interventions, which may not adequately meet the specific needs of people experiencing SMI who are making a cessation attempt. Moreover, the exclusion of people experiencing SMI from many large randomised control trials (RCTs) investigating the safety and efficacy of pharmacological smoking treatments means that the evidence for their use in this population is limited (Talukder et al., 2021).

Barriers due to personal circumstances (e.g. low socioeconomic status, lack of family and peer support, co-morbid physical health problems) are more prevalent in people experiencing SMI (Sweeney et al., 2015). Additional barriers include commonly held misconceptions around the benefits of smoking in managing symptoms associated with mental illness, such as smoking reduces stress (Morisano et al., 2013; Strand and Nybäck, 2005), and that smoking cessation may worsen mental health symptoms, despite good evidence for the converse being true (Taylor et al., 2021).

Tailored cessation interventions for people experiencing SMI include the Smoking Cessation Intervention for Severe Mental Illness (SCIMITAR+) study (Gilbody et al., 2019). This large RCT, conducted in the United Kingdom, found that people with SMI who received the bespoke intervention had 2.4 times greater odds of quitting smoking and remaining abstinent at 6 months follow-up compared to the treatment as usual group. Some caveats should be noted, however, including first, that intention-to-treat analysis was not used as typically reported in smoking trials, and second, at 12 months the effect was not significant. This suggests that more research is needed to identify how sustained abstinence and longer-term abstinence can be supported in people experiencing SMI.

Prior studies have measured the effectiveness of different pharmacological aids on both cessation and relapse prevention in people experiencing SMI. Varenicline and bupropion have each been found to increase the likelihood of cessation in people experiencing SMI, with neither having a detrimental effect on psychiatric symptoms (Tidey and Miller, 2015; Tsoi et al., 2013). EAGLES, a large RCT comparing individuals experiencing mental illness to a sample without mental illness provided further support for the efficacy and safety of these pharmacological aids, though the sample predominantly consisted of individuals experiencing affective disorders and the proportion of participants included with a psychotic disorder was limited (Anthenelli et al., 2016).

Despite the numerous studies trialling cessation treatments for people experiencing SMI, to date, little is known about the specific factors that contribute to sustained abstinence in people experiencing SMI. Given the additional challenges that people with SMI experience in quitting smoking, maintaining abstinence is of high importance. This review seeks to address this gap by assessing the current evidence for associations of sustained abstinence in people experiencing SMI. Elucidating the factors that aid in successful abstinence may help in both the development and planning of appropriate interventions and in identifying individuals who may need targeted support to prevent relapse.

Aim

To identify factors that are associated with sustained smoking abstinence in people experiencing SMI after participation in a smoking intervention.

Methods

Design

The systematic review examined all original research studies that measured sustained abstinence in people experiencing SMI after participation in a smoking intervention. The review was conducted in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement and was pre-registered on PROSPERO (CRD42020168279).

Criteria for inclusion in the review

Studies

Original peer-reviewed randomised and non-randomised studies, including single-arm studies, that examined factors associated with successful smoking abstinence in people experiencing SMI after participation in a smoking intervention were included. Grey literature, editorials, theses, conference abstracts and articles not published in English were not included. Reviews were not included but were checked for additional references. Secondary references that reported on the same dataset as a primary reference (for instance, an additional follow-up time point) were included and acknowledged in the data tables.

Intervention

Studies were included that described an intervention to assist participants to cease tobacco smoking, and that had a minimum follow-up period of 3 months following the completion of the intervention. These included both behavioural and pharmacological interventions, or a combination. Studies that included enforced smoking cessation (e.g. upon hospital admission) were not included if (1) the intervention was not optional or (2) no pharmacological or behavioural support was provided upon discharge. Observational studies of individuals completing interventions not delivered by the research team (e.g. national smoking helplines and quit programmes) could be included. Studies investigating the use of e-cigarettes were not included, as globally there is currently limited evidence on effectiveness and safety, and they are currently only licenced for smoking cessation in a limited number of countries.

Relapse prevention trials were included if the preceding smoking intervention was described in sufficient detail to allow the relevant outcomes to be extracted from the data.

Participants

Eligible studies included those with participants aged 18 years or older who had experienced SMI. SMI was defined as meeting the criteria for a clinical diagnosis of schizophrenia, schizoaffective disorder, bipolar disorder or other psychotic disorder. Studies were also included if participants were recorded as experiencing an SMI without further detail on the diagnosis being provided. If so, this was recorded in the data extraction.

Studies with mixed-diagnosis samples (e.g. people experiencing different mental illnesses, or in which people experiencing mental illness were a subgroup of the general population) were included if 75% of the sample or greater reported SMI, or if the relevant outcomes could be extracted from the data for the SMI sample separately.

Outcomes

Primary outcomes

Primary outcomes were any factors associated with sustained smoking abstinence in people experiencing SMI. All factors identified were documented and grouped as characteristics of the cessation programme (e.g. type of treatment, attendance), socio-demographic characteristics, clinical characteristics (e.g. symptoms related to mental illness or psychiatric medication) and smoking history.

The measure of abstinence at the latest follow-up was used as the time point to identify factors associated. Where more than one measure of abstinence was provided (i.e. point-prevalence and continuous abstinence), the association with each was reported. All available abstinence outcomes were recorded when describing the characteristics of studies.

Secondary outcome

A secondary outcome was the identification of factors associated with smoking relapse. Relapse was defined as a return to regular smoking. The measures used by each study to establish relapse were recorded.

Search strategy and study selection

Searches were conducted using PubMed, PsycInfo, Scopus, Embase, Emcare, CINAHL and Cochrane Library from the inception of the e-databases until June 2022. Search terms included ‘smoking cessation’, ‘severe mental illnesses’, ‘smoking relapse’ and their synonyms. The full search strategy is included in Appendix 1 of Supplemental material. Two authors (K.D. and M.S-M.) undertook screening of titles and abstracts independently. The full-text screening was completed by the same two authors and disagreements were discussed and settled with a third (J.M.L.) and fourth (R.J.C.) author.

Data extraction

Two authors (K.D. and M.S-M.) independently extracted the data into a standardised data extraction table. Any discrepancies were settled by a third reviewer (J.M.L.). Variables extracted are shown in Table 1.

Table 1.

Variables extracted from included studies.

Category	Variables
Methods	Study design, country, recruitment, setting (e.g. inpatient versus community)
Participants	Number, demographic characteristics (age, gender, SMI diagnosis), proportion of sample with a diagnosed SMI, criteria for determining SMI diagnosis
Intervention	Type, length, number of sessions, mode of delivery
Smoking outcomes – Abstinence	Correlates of sustained smoking abstinence, method of measuring abstinence, proportion reporting abstinence at treatment end, proportion reporting abstinence at latest follow-up period, smoking dependence (Fagerstrom score)
Smoking outcomes – Relapse	Correlates of smoking relapse, time to relapse

SMI: severe mental illness.

Assessment of risk of bias

For references that reported on the same study but contributed data for different time points, risk of bias assessments were conducted, and reported, per reference. This approach was used to account for the potential difference in methods of data collection and measurement of abstinence at each time point. Where more than one reference referred to the same study and provided data for the same time point (i.e. different analyses of associations), risk of bias assessments were conducted for the primary reference for that study and encompassed all available information from the combined references.

References in which the studies utilised a randomised study design were assessed for risk of bias using version 2 of the Cochrane ‘Risk of Bias’ tool (RoB2; Bucklin, 2021). Each study was assessed on the following five domains: (1) risk of bias arising from the randomisation process, (2) risk of bias due to deviations from the intended interventions (effect of assignment to intervention), (3) risk of bias due to missing outcome data, (4) risk of bias in measurement of the outcome, and (5) risk of bias in selection of the reported result. Where no data analysis plan was publicly available, neither via publication nor via trial registration, domain 5 was coded as ‘no information’ resulting in a ‘some concerns’ outcome.

References of non-randomised study designs were assessed using the ROBINS-I tool (Sterne et al., 2016). This tool assesses bias across seven domains: (1) bias due to confounding, (2) bias in selection of participants, (3) bias in classification of interventions, (4) bias due to deviations from intended intervention, (5) bias due to missing data, (6) bias in measurement of outcomes, and (7) bias in selection of the reported result.

Assessments were completed by two authors (K.D. and R.M.). Consensus judgements for each domain and overall are presented.

Data synthesis and analysis

Data on factors related to sustained abstinence following participation in a smoking cessation or relapse prevention intervention were synthesised following the Cochrane guidance for appropriate synthesis without meta-analysis (McKenzie and Brennan, 2022). Effect estimates are summarised using descriptive statistics, from which odds ratios (ORs) were calculated to provide a standardised metric where the data available permitted. Where possible, median OR and ranges are reported for each factor assessed for a relationship with sustained abstinence. Given that measurement method and duration of follow-up have been found to affect estimates of abstinence (West et al., 2005), and the different lengths of follow-up and measurement used to assess abstinence reported by references included in this review, the results are presented separately for short-term (<6 months), medium-term (6–12 months) and long-term follow-ups (>12 months), and for point-prevalence versus continuous measures of abstinence. Smoking relapse prevention trials are denoted in the tables.

Meta-analysis of the effect of intervention on sustained abstinence

Meta-analysis examining the effect of receiving any intervention versus no intervention was used to estimate the overall difference in odds of smoking abstinence. As studies reported abstinence using different metrics, both a point-prevalence meta-analysis and a continuous abstinence meta-analysis were completed.

We had planned to conduct subgroup analyses to examine the effects of different intervention types (e.g. behavioural interventions, pharmacological interventions), however, were unable to do so due to the heterogeneity within therapy types. For instance, the behavioural interventions encompassed a variety of approaches and were often provided in conjunction with different pharmacological aids, meaning that the effects of each could not be separated.

A random effects model was used to estimate odds of abstinence, overall, and for subgroups of less than 6 months, 6–12 months and more than 12 months follow-up time.

Heterogeneity of effects was examined. Possible publication bias was assessed by funnel plots, Egger’s test, trim and fill. The overall effect size was re-estimated to account for possible bias (Henmi & Copas, 2010). Analyses were performed using the package ‘metafor’ in ‘R’.

Results

After the removal of duplicates, a total of 1498 results were identified to be screened. Of these, 26 references met the inclusion criteria. As six of the studies provided additional follow-up data to four studies already included, a total of 20 studies were included in the final sample (Figure 1).

Figure 1.

Study inclusion flow diagram based on PRISMA guidelines.

Summary of study characteristics

The majority of studies included were randomised controlled trials. Three non-randomised trials were included (Addington et al., 1998; Cather et al., 2013; Garcia-Portilla et al., 2016) as shown in Table 2. Three studies (four references) consisted of a cessation intervention phase followed by a relapse prevention phase (Cather et al., 2013; Evins et al., 2014; Horst et al., 2005; Thorndike et al., 2016). All but two studies included a control condition (Addington et al., 1998; Cather et al., 2013), typically a pharmacological placebo. All studies were conducted in high-income countries.

Table 2.

Characteristics of studies.

Author	Country	Sample size (N)	Participant age M (SD)	Mental health diagnoses of cohort	Study type	Intervention type	Intervention detail	Intervention length	Control group
Addington et al. (1998)	Canada	50	40 (8.0)	Schizophrenia, schizoaffective disorder	Pre-/post-intervention (single-arm non-RCT)	Behavioural	Manualised group programme, optional NRT	10 weeks	No control group
Baker et al. (2006) ^a	Australia	298	37.2 (11.1)	Psychotic disorder	Two-arm RCT	Combined behavioural/pharmacological	Motivational interviewing, CBT, NRT	10 weeks	Treatment as usual (including access to GP, publicly funded community mental health teams and general smoking cessation information)
Baker et al. (2015) ^b	Australia	235	41.6 (11.1)	Schizophrenia spectrum disorder, bipolar disorder, nonorganic psychosis	Two-arm RCT	Combined behavioural/pharmacological	Motivational interviewing, CBT, contingent reinforcement, NRT	Behavioural intervention; 9 months NRT; 24 weeks	Motivational interviewing and CBT at initial assessment, NRT for 24 weeks
Chengappa et al. (2014)	United States	60	Intervention 45.7 (10.3) Control 46.2 (8.5)	Bipolar disorder (I, II or not otherwise specified)	Double-blind, placebo-controlled RCT	Combined behavioural/pharmacological	Smoking cessation counselling, Varenicline	12 weeks	Placebo, smoking cessation counselling
Evins et al. (2001) ^c	United States	18	Intervention 45.5 (7.2) Placebo 42.7 (7.9)	Schizophrenia	Double-blind RCT with placebo	Combined behavioural/pharmacological	Group CBT programme, Bupropion	Behavioural intervention: 9 weeks Bupropion 12 weeks	Placebo, group CBT programme
Evins et al. (2005)	United States	53	Intervention 46 (9.4) Placebo 45.5 (8.3)	Schizophrenia, schizoaffective disorder (depressed type)	Double-blind RCT with placebo	Combined behavioural/pharmacological	Group CBT programme, Bupropion	Behavioural intervention 12 weeks Bupropion; 12 weeks	Placebo and group CBT programme
Evins et al. (2007)	United States	51	Intervention 44.8 (9.2) Placebo 43.6 (10.9)	Schizophrenia	Double-blind RCT with placebo	Combined behavioural/pharmacological	Group CBT programme, Bupropion, NRT	Behavioural intervention: 12 weeks Bupropion 12 weeks	Placebo, NRT, group CBT programme
Garcia-Portilla et al. (2016)	Spain	75	Varenicline group 45.0 (9.4) Nicotine patch group (control) 45.7 (8.6)	Schizophrenia, schizoaffective disorder, bipolar disorder.	Two-arm non-randomised, open-label trial.	Combined behavioural/pharmacological	Individual motivational therapy, group therapy, NRT, Varenicline	12 weeks	NRT (patches), individual motivational therapy, group therapy
George et al. (2000)	United States	45	Intervention 41.6 (7.9) Control 36.6 (9.5)	Schizophrenia, schizoaffective disorder	Two-arm RCT	Combined behavioural/pharmacological	Group therapy (motivational therapy, psychoeducation, social skills training, relapse prevention training) NRT	10 weeks	Standard American Lung Association group therapy, group counselling, NRT
George et al. (2002)	United States	32	Intervention 45.4 (11.9) Placebo 40.9 (9.4)	Schizophrenia, schizoaffective disorder	Double-blind RCT with placebo	Combined behavioural/pharmacological	Group therapy (motivational therapy, psychoeducation, social skills training, relapse prevention training), Bupropion	10 weeks	Placebo, group therapy (as in intervention group)
George et al. (2008)	United States	58	Intervention 41.2 (9.2) Control 39.3 (6.9)	Schizophrenia, schizoaffective disorder	Double-blind RCT with placebo	Combined behavioural/pharmacological	Group therapy (Motivational therapy, psychoeducation, social skills training, relapse prevention training), NRT, Buproprion	Behavioural intervention 10 weeks NRT 8 weeks Bupropion 9 weeks	Placebo, NRT (patch), group therapy
Gilbody et al. (2015)	United Kingdom	97	Intervention: 47.3 (40.6–56.9) Control 46.4 (35.2–53.5)	Schizophrenia or a delusional or psychotic illness	Pilot RCT	Behavioural support, pharmacological support referred on	Behaviour change support, home visits, usual care, NRT may be prescribed outside of the study	Not detailed	Treatment as usual including GP and publicly available resources
Gilbody et al. (2019)	United Kingdom	526	Total 46.0 (12.1) Intervention 46.5 (12.5) Control 45.5 (11.7)	Schizophrenia, delusional or psychotic disorder, bipolar disorder	Pragmatic RCT	Behavioural support, pharmacological support referred on	Behaviour change support, home visits, usual care, NRT may be prescribed outside of the study	Not detailed (12 sessions)	Treatment as usual including GP and publicly available resources
Jaen-Moreno et al. (2021)	Spain	160	Intervention 48.45 (5.92) Control 49.41 (6.09)	Schizophrenia, bipolar disorder	Two-arm, open-label RCT	Behavioural	Personalised information about the lung damage, motivational SMS	Not detailed	Active control, 30 min education on benefits of smoking cessation
Rogers et al. (2017)	United States	384	Intervention 43.7 (13.3) Control 43.1 (13.6)	Schizophrenia, schizoaffective disorder or bipolar disorder	Two-arm RCT	Combined behavioural/pharmacological	Counselling, motivational interviewing, relapse prevention, optional NRT	Behavioural intervention not detailed NRT up to 12 weeks	Quitline (one telephone counselling, plus one follow-up. Up to 2 weeks NRT)
Williams et al. (2010)	United States	87	Treatment of Addiction to Nicotine in Schizophrenia (TANS) 43.5 (12.1) Medication Management (MM) 47.1 (10.5)	Schizophrenia, schizoaffective disorder	Comparative, randomised study of two manualised behavioural counselling approaches	Combined behavioural/pharmacological	Motivational interviewing, social skills training, use of NRT, and relapse prevention strategies	Behavioural intervention 26 weeks NRT 16 weeks	Less intensive intervention (medication management), NRT
Williams et al. (2012)	United States and Canada	127	Varenicline 40.2 (11.9), Control 43.0 (10.2)	Schizophrenia, schizoaffective disorder	Double-blind placebo-controlled RCT	Combined behavioural/pharmacological	Counselling, Varenicline	Counselling 24 weeks Varenicline 12 weeks	Placebo, counselling
Relapse Prevention Trials
Cather et al. 2013	Unites States	17¹	47.1(4.7)	Schizophrenia, schizoaffective disorder	Prospective relapse prevention intervention trial	Combined behavioural/pharmacological	Initial intervention: Group CBT, Bupropion, NRT Relapse prevention: continued pharmacotherapy (no dosage change) and continued group CBT	15 months (3 months initial intervention, 12 months relapse prevention)	No control group
Evins et al. 2014^d	United States	87²	Intervention 51.4 (9.6) Placebo 45.7 (10.3)	Schizophrenia, schizoaffective disorder, bipolar disorder	Randomized, double-blind, placebo-controlled, parallel-group, relapse-prevention clinical trial	Combined behavioural/ pharmacological	Initial intervention: Group CBT, Varenicline Relapse prevention: Continued Varenicline and tapered group CBT	52 weeks (12 weeks initial intervention, 40 weeks relapse prevention)	Placebo, group CBT
Horst et al. 2005	United States	18³	N/A	Schizophrenia or schizoaffective disorder	Two-phases relapse prevention trial (phase 1 –open-label, phase 2 – single blind RCT)	Combined behavioural/ pharmacological	Initial intervention: Group health education, NRT Relapse prevention: Informal education and motivational discussion, NRT	9 months (3 months initial intervention, 6 months relapse prevention)	Placebo, informal education and motivational discussion

SD: standard deviation; NRT: nicotine replacement therapy; RCT: randomised control trial; CBT: cognitive behavioural therapy.

Baker et al. (2010) provide 4-year follow-up data for this study; Filia et al. (2014) provide secondary analysis of this study to investigate gender differences.

Baker et al. (2018) provide 36-month follow-up data or this study; Clark et al. (2017) provides secondary analysis of this study.

Evins et al. (2014) provide 2-year follow-up data for this study.

Thorndike et al. (2016) provided a secondary analysis to Evins et al. 2014.

The sample is 17 of 41 from initial intervention, who met the criteria of 7-day point prevalence abstinence at post-intervention

The sample is 87 of 203 from initial intervention, who were randomised to the relapse prevention phase after demonstrating 14-day continuous abstinence

The sample is 18 of 50 from initial intervention who reported quitting smoking at end of initial intervention, defined as 7-day point prevalence verified by a CO monitor

Participant characteristics

All studies included samples in which all participants had a diagnosis of SMI (Table 2). Half of the studies recruited from mental health or health services, while other methods included via primary care, media campaigns, research registers and self-referral.

Intervention characteristics

The majority of study interventions provided a combination of pharmacological treatment alongside psychosocial approaches (Table 3). Psychosocial approaches included group cognitive behavioural therapy (CBT) programmes (n = 5; Cather et al., 2013; Evins et al., 2001, 2005, 2007, 2014), individual CBT programmes (n = 2; Baker et al., 2006, 2015), motivational interviewing (n = 8; Baker et al., 2006, 2015; Garcia-Portilla et al., 2016; George et al., 2000, 2002, 2008; Rogers et al., 2017; Williams et al., 2010), smoking cessation counselling (n = 3; Chengappa et al., 2014; Rogers et al., 2017; Williams et al., 2012) and education programmes including relapse prevention (n = 6; George et al., 2000, 2002, 2008; Horst et al., 2005; Jaen-Moreno et al., 2021; Williams et al., 2010). Other approaches included contingent reinforcement (Baker et al., 2015) and existing group programmes adapted for people experiencing SMI (Addington et al., 1998; Gilbody et al., 2015, 2019). The majority of interventions included more than one approach.

Table 3.

Smoking intervention types.

Intervention type	Number of interventions
Psychosocial intervention only	4
Pharmacological intervention only	0
Combined psychosocial and pharmacological interventions	16
NRT + psychosocial intervention	6
Bupropion + psychosocial intervention	3
Varenicline + psychosocial intervention	3
Combination of Bupropion and NRT + psychosocial intervention	3
Combination of Varenicline and NRT + psychosocial intervention	1

NRT: nicotine replacement therapy.

Smoking outcomes characteristics

Rates of smoking abstinence

Abstinence at the end of smoking cessation interventions ranged between 11.0% and 50.0% (n = 12) when assessed via point-prevalence, and between 10.9% and 37.5% (n = 9) when continuous abstinence was measured. Sustained abstinence assessed via point-prevalence at the latest follow-up ranged between 6.6% and 45.0% (n = 15), and when assessed via continuous abstinence ranged between 5.4% and 19.0% at 6 months, and 3.9% and 14.3% at 12 months. Abstinence following relapse prevention trials ranged between 45.0% and 64.7% (n = 1) when measured via point-prevalence, and between 45.0% and 77.6% (n = 3) when assessed via continuous abstinence at 12 months of relapse prevention (Table 4). Further information on the measurement of abstinence in the included references is available in Supplementary 1.

Table 4.

Smoking outcomes.

Author	Measure of abstinence	Baseline FagerstromscoreM (SD)	Follow-up period (after intervention)	% abstinent at study end (point-prevalence)	% abstinent at study end (continuous abstinence)	% abstinent at follow-up (point-prevalence)	% abstinent at follow-up (continuous abstinence)	Intervention significant at the latest follow-up
Addington et al. (1998)	7-day point-prevalence through self-report biochemically verified by urinary cotinine levels	6.4 (2.1)	3 months, 6 months (after the last group session)	42.0% (n = 21)	Not measured	3 months: 16.0% (n = 8) 6 months: 12.0% (n = 6)	Not measured	Yes (compared to pre-intervention)
Baker et al. (2006)	7-day point prevalence verified by CO reading < 10 ppm Continuous abstinence measured by self-report until end of study (12 weeks) and until 6- and 12-month follow-ups	Intervention: 7.9 (2.1) Control: 8.2 (2.1)	6 and 12 months after the initial assessment	Intervention: 15.0% Control: 6.0%	Intervention: 10.9% Control: 4.0%	6 months Intervention: 9.5% Control: 4.0% 12 months Intervention: 10.9% Control: 6.6%	6 months Intervention: 5.4% Control: 2.0% 12 months Intervention: 3.4% Control: 0.7%	No
Baker et al. (2010) Secondary analysis of the study by Baker et al. (2006)	7-day point-prevalence verified by CO reading < 10 ppm Continuous abstinence measured by self-report from quit date up until 1- and 4-year follow-up	As above	1 year, 4 years (after baseline assessment)	As in the study by Baker et al. (2006)	As in the study by Baker et al. (2006)	1 year Intervention: 14.2% Control: 9.2% 4 years Intervention: 21.0% Control: 15.7%	1 year Intervention: 3.9% Control: 0.8% 4 years Intervention: 2.4% Control: 0%	Yes (at 1 year only)
Baker et al. (2015)	7-day point-prevalence self-report verified by CO reading < 10 ppm	Intervention: 6.8 (2.2) Control: 6.8 (1.8)	12 months (from baseline assessment)	Not measured 15-week midpoint: Intervention: 11.0% Control: 12.0%	Not measured	12 months Intervention: 6.6% Control: 6.2%	Not measured	No
Baker et al. (2018) Secondary analysis of the study by Baker et al. (2015)	7-day point-prevalence verified by CO reading < 10 ppm	As in the study by Baker et al. (2015)	18 months, 24 months, 30 months, 36 months from baseline assessment	As in the study by Baker et al. (2015)	Not measured	12 months Intervention: 6.6% Control: 6.2% 18 months Intervention: 9.0% Control: 8.0% 24 months Intervention: 9.0% Control: 8.0% 30 months Intervention: 11.0% Control: 12.0% 36 months Intervention: 11.0% Control: 8.0%	Not measured	No
Chengappa et al. (2014)	7-day point-prevalence and 4-week continuous abstinence measured by self-report and verified by CO reading < 10 ppm at weeks 12 and 24	Intervention: 6.4 (1.7) Control: 5.9 (1.9)	24 weeks from baseline (12 weeks after the end of intervention)	Intervention: 48.4% (n = 15) Control: 10.3% (n = 3)	4-week CA Intervention: 35.5% (n = 11) Control: 10.3% (n = 3)	Intervention: 19.4% (n = 6) Control: 6.9% (n = 2)	Not measured	No
Clark et al. (2017) Secondary analysis of the study by Baker et al. (2015) investigating predictors of abstinence	7-day point-prevalence self-report verified by CO reading < 10 ppm	6.8 (2)	12 months from baseline	Not reported (Original results published by Baker et al., 2015)	Not measured	Not reported (Original results published by Baker et al., 2015)	Not measured	No comparison conducted
Evins et al. (2001)	7-day point-prevalence self-report verified by CO reading < 9 ppm at treatment end and follow-up Sustained abstinence is defined as consecutive weekly CO readings < 9 ppm throughout the treatment phase and follow-up for a total of 16 weeks	N/A	12 weeks (24 weeks from baseline)	Intervention: 11.0% (n = 1) Control: 0%	Intervention: 11.0% (n = 1) Control: 0%	Intervention: 11.0% (n = 1) Control: 0%	Not measured	No
Evins et al. (2004) Secondary analysis providing 2-year follow-up data to the study by Evins et al. (2001)	7-day point-prevalence self-report verified by CO reading < 9 ppm	N/A	2 years from baseline	As in the study by Evins et al. (2001)	As in the study by Evins et al. (2001)	Intervention: 22.0% (n = 2) Control: 22.0% (n = 2) (one participant in the placebo group received bupropion during the follow-up period)	Not measured	No
Evins et al. (2005)	7-day point-prevalence self-report verified by CO reading < 9 ppm 4 week continuous abstinence measured by self-report and verified by CO reading < 9 ppm each week for weeks 9–12 of the trial	Intervention: 4.5. (1.5) Control: 4.0 (1.4) (Heaviness of Smoking Index Q’s only)	3 months after the end of intervention	Intervention: 16.0% (n = 4) Control: 0%	Intervention: 16.0% (n = 4) Control: 0%	Intervention: 4.0% (n = 1) Control: 3.6% (n = 1)	Not measured	No
Evins et al. (2007)	Continuous abstinence is defined as 7-day point-prevalence at each follow-up assessment measured via self-reports and verified by CO reading < 8 ppm, for up to 52 weeks	Intervention: 7.2 (1.9) Control: 7.1 (1.7)	3 months, 12 months from the target quit date (between weeks 4 and 5 of the 12-week intervention)	Not reported separate to continuous abstinence	Intervention: 36.0% (n = 9) Control: 19.0% (n = 5)	Not reported separate to continuous abstinence	3 months Intervention: 20.0% (n = 5) Control: 8.0% (n = 2) 12 months Intervention: 12.0% (n = 3) Control: 8.0% (n = 2)	No
Filia et al. (2014) Secondary analysis of the study by Baker et al. (2006)	7-day point-prevalence self-report verified by CO reading < 10 ppm Continuous abstinence measured from nominated quit date via self-report and CO reading at 3-, 6- and 12-month assessments	Male: 7.7 (2.2) Female: 8.4 (1.9)	6 and 12 months from baseline	Male: 9.0% Female: 12.0% (*3-month assessment is the first data point for gender difference analyses)	Male: 6.4% Female: 8.5% (*3-month assessment is the first data point for gender difference analyses)	6 months Male: 5.1% Female: 8.5% 12 months Male: 7.7% Female: 9.2%	6 months Male: 3.2% Female: 4.2% 12 months Male: 1.9% Female: 2.1%	No (gender differences compared)
Garcia-Portilla et al. (2016)	7-day point-prevalence self-report verified by CO reading < 9 ppm	Total: 6.3 (2.6) Varenicline: 6.9 (1.8) Nicotine patch: 5.6 (3.1)	24 and 36 weeks from baseline	Varenicline: 48.6% (n = 17) Nicotine patch: 50.0% (n = 20)	Not measured	24 weeks Varenicline: 37.1% (n = 13) Nicotine patch: 45.0% (n = 18) 36 weeks Varenicline: 28.6% (n = 10) Nicotine patch: 45.0% (n = 18)	Not measured	No
George et al. (2000)	Point-prevalence (duration not specified) self-report verified by CO reading < 10 ppm Continuous abstinence reported for last 4 weeks of trial, measurement not specified	Intervention: 7.1 (1.6) Control: 6.3 (1.6)	6 months after study completion	Intervention: 35.7% (n = 10) Control: 35.3% (n = 6)	Intervention: 32.1% (n = 9) Control: 23.5% (n = 4)	Intervention: 10.7% (n = 3) Control: 17.6% (n = 3)	Not reported	No
George et al. (2002)	7-day point-prevalence self-report verified by CO reading < 10 ppm Continuous abstinence reported for last 4 weeks of trial, measured via weekly self-reports of 7-day abstinence verified by CO < 10 ppm	Intervention: 7.1 (0.9) Control: 7.3 (1.6)	6 months after study completion	Intervention: 50.0% (n = 8) Control: 12.5% (n = 2)	Intervention: 37.5% (n = 6) Control: 6.3% (n = 1)	Intervention: 18.8% (n = 3) Placebo: 6.3% (n = 1)	Not measured	No
George et al. (2008)	7-day point-prevalence self-report verified by CO reading < 10 ppm Continuous abstinence reported for last 4 weeks of trial, measured via weekly self-reports of 7-day abstinence verified by CO < 10 ppm	Intervention: 6.8 (1.8) Control: 6.8 (1.7)	6 months post-quit date	Intervention: 34.5% (n = 10) Control: 10.3% (n = 3)	Intervention: 27.6% (n = 8) Control: 3.4% (n = 1)	Intervention: 13.8% (n = 4) Control: 0%	Not measured	No
Gilbody et al. (2015)	7-day point-prevalence self-report verified by CO reading < 10 ppm, self-report accepted where CO unavailable	Intervention: 6.0 (2.6) Control: 6.1 (2.2)	12 months	Not reported	Not reported	Intervention 36.0% (n = 12) Control 23.0% (n = 8)	Not measured	Not reported
Gilbody et al. (2019)	7-day point-prevalence self-report verified by CO reading < 10 ppm, self-report accepted where CO unavailable	Intervention: 6.5 (2.0) Control: 6.4 (1.9)	6 and 12 months from randomisation (baseline)	Intervention: 11.0% (n = 32) Control: 5.0% (n = 14) 6-month data are the earliest time-point, length of intervention not detailed	Not measured	Intervention: 13.0% (n = 34) Control: 8.0% (n = 22) (*at 12-month follow-up)	Not measured	No
Jaen-Moreno et al. (2021)	7-day point-prevalence abstinence measured as self-reported verified by CO < 10 ppm	Intervention: 5.8 (2.1) Control: 5.8 (2.3)	12, 24 and 48 weeks post-intervention	Not reported	Not reported	12 weeks: Intervention: 7.3% (n = 6) Control: 2.6% (n = 2) 24 weeks: Intervention: 8.5% (n = 7) Control: 5.1% (n = 4) 48 weeks: Intervention: 7.3% (n = 6) Control: 3.9% (n = 3)	Not measured	No
Rogers et al. (2017)	Self-report 30-day abstinence (point-prevalence)	Not measured	2 and 6 months post-randomisation	Not reported	Not reported	6 months: Intervention: 18.6% (n = 38) Control: 16.1% (n = 29)	Not measured	No
Williams et al. (2010)	Continuous abstinence is defined as self-reported abstinence from the quit date up until 12 (study end), 26 and 52 weeks Self-reports were confirmed by exhaled CO < 10 ppm at the corresponding visit 7-day point-prevalence abstinence measured as self-reported verified by CO < 10 ppm	TANS Intervention: 5.9 (2.0) MM Intervention: 5.8 (1.83)	12 months from baseline	Not reported	TANS Intervention: 15.6% MM Intervention: 19.0%	Not measured	6 months TANS Intervention: 15.6% MM Intervention: 19.0% 12 months TANS Intervention: 13.3% MM Intervention: 14.3%	No
Williams et al. (2012)	7-day point-prevalence verified by CO reading < 10 ppm	Varenicline: 6.6 (1.7) Placebo: 6.3 (1.6)	24 weeks (12 weeks after study end)	Varenicline: 19% Placebo: 4.7%	Not measured	Varenicline: 11.9% Placebo: 2.3%	Not measured	No
Relapse prevention trials
Cather et al. (2013)	7-day point-prevalence verified by CO reading Self-reported 4-week continuous abstinence	7 (1.5)	15 months (12 months of relapse prevention from abstinence date)	100% (41.5%, n = 17, of original sample) of participants entering relapse prevention stage	Of those entering the relapse prevention stage at end of initial intervention (n = 17): 14-day continuous abstinence: 82.0% (n = 14) 28-day continuous abstinence: 71.0% (n = 12)	64.7% (n = 11) (*at end of the relapse prevention trial)	58.8% (n = 10) (*at end of the relapse prevention trial)	No comparison group
Evins et al. (2014)	7-day point-prevalence self-report verified by CO reading < 9 ppm Continuous abstinence is defined as point-prevalence at that visit and all preceding visits (ranged between weekly and 4-weekly, for a maximum of 64 weeks Continuous abstinence measured by self-report only between 64 and 76 weeks)	Intervention: 5.9 (2.0) Control: 5.9 (1.7)	64 and 76 weeks from baseline (12 and 24 weeks after the end of relapse prevention phase) Relapse prevention intervention ended at 52 weeks	Not measured at end of the initial phase. At end of the relapse prevention phase: Intervention: 60.0% (n = 24) Control: 19.0% (n = 9)	100% (42.9%, n = 87, of original sample) of participants entering the relapse prevention phase At end of the relapse prevention phase: Intervention: 45.0% (n = 18) Control: 15.0% (n = 7)	64 weeks Intervention: 45.0% (n = 18) Control: 13.0% (n = 6) 7-day point-prevalence not measured at 76 weeks	64 weeks Intervention: 40.0% (n = 16) Control: 11.0% (n = 5) 76 weeks Intervention: 30.0% (n = 12) Control: 11.0% (n = 5)	Yes
Horst et al. (2005)	7-day point-prevalence measured via CO reading < 10 ppm Relapse was defined as two consecutive readings > 10 ppm Continuous abstinence considered as continued 7-day CO readings < 10 ppm	Intervention: 7.8 (1.2) Control: 7.8 (1.6) (*At start of relapse prevention phase)	6 months (at end of the relapse prevention phase)	100% (36.0%, n = 18, of original sample) of participants entering the relapse prevention stage	Not measured	Not measured	Intervention: 67.0% (n = 6) Control: 0% > 10 ppm	Yes
Thorndike et al. (2016) Secondary analysis of the study by Evins et al. (2014)	7-day point-prevalence self-report verified by CO reading < 9 ppm Continuous abstinence is defined as point-prevalence at that visit and all preceding visits (ranged between weekly and 4-weekly, for a maximum of 64 weeks. Continuous abstinence measured by self-report only between 64 and 76 weeks)	Relapse group: 5.9 (2.0) Abstinence group: 6.0 (1.9) (*Reported at baseline)	52 weeks (from baseline, at end of relapse prevention intervention)	Not measured at end of the initial phase	100% (32.0%, n = 65, of original sample) of participants entering the relapse prevention phase	Not measured	At the end relapse prevention phase: Varenicline: 77.4% (n = 24) Placebo: 23.7% (n = 9)	Yes – reported in the study by Evins et al. (2014)

SD: standard deviation; ppm: parts per million; CA: continuous abstinence; TANS: treatment of addiction to nicotine in schizophrenia; MM: medication management.

Relapse to smoking

Relapse rates were explicitly reported in four studies (Chengappa et al., 2014; Evins et al., 2014; Garcia-Portilla et al., 2016; Horst et al., 2005), and two reported time to relapse (Evins et al., 2014; Williams et al., 2010). Only one study examined factors associated with relapse (Horst et al., 2005) (Table 4).

Factors associated with abstinence

Intervention-related characteristics

Treatment condition was the factor most commonly measured as a correlate of sustained smoking abstinence: examined by 21 of the included references. This included one study with a follow-up of less than 6 months (Evins et al., 2005) assessed to be at moderate risk of bias (i.e. some concerns), with a standardised OR of 1.13, (95% confidence interval [CI] = [0.07, 18.98]) which was not significant.

Fourteen references with a 6- to 12-month follow-up examined the association with abstinence using point-prevalence measures. The median OR of sustained abstinence was 1.97 (range: 0.49–10.42) for interventions versus control conditions, and three references reported a significant association (Evins et al., 2014; George et al., 2000; Horst et al., 2005). Of these, two were considered at moderate risk of bias and one at high risk. Two were relapse prevention trials. Four references with a 6- to 12-month follow-up examined the association with abstinence using continuous abstinence measures. The median OR of sustained abstinence was 2.48 (range: 0.92–5.28) for intervention compared to control conditions. None reported a significant association. All were considered at moderate risk of bias.

In references with a follow-up longer than 12 months, three examined the association using point-prevalence measures of abstinence. The median OR of sustained abstinence was 1.0 (range: 0.70–1.36) for interventions compared to control conditions and none reported a significant association. One was at low risk of bias, one at moderate risk and one at high risk. Two references examined the association using continuous abstinence measures. One did not provide data beyond a non-significant report (Baker et al., 2010). One was significant in favour of the intervention (OR = 3.4, 95% CI = [1.02, 13.6]) and was a relapse prevention trial (Evins et al., 2014). Both were assessed at moderate risk of bias.

One reference examined the association between participant-rated therapeutic relationship and sustained smoking abstinence (Williams et al., 2010). This study, considered at moderate risk of bias, used continuous abstinence measures at a 3-month follow-up and reported a significant relationship (p = 0.03) in favour of higher ratings.

Programme attendance during intervention was measured by seven references. Four with a 6- to 12-month follow-up examined the association with abstinence using point-prevalence measures. The median OR of sustained abstinence was 2.17 (range: 1.04–3.22) for higher compared to lower attendance and two reported a significant association (Addington et al., 1998; Baker et al., 2006). Of these, one was considered at moderate risk of bias and one at high risk. Three references examined the association with abstinence using continuous abstinence measures, two were considered at moderate risk of bias and one high risk. A median OR could not be calculated due to lack of suitable data, and one reference reported a significant relationship in the direction of higher attendance. Only one reference examined the association at a follow-up greater than 12 months and was considered at moderate risk of bias. This reference did not report a significant relationship.

Participant characteristics

Three references examined gender as a factor associated with sustained abstinence at 6–12 months, one was assessed at low risk of bias and two at moderate risk. For references using point-prevalence measures, the median OR of abstinence was 2.02 (range: 1.33–4.57) for female participants compared to male. One reference reported a significant effect (Clark et al., 2017), with females over 4.5 times more likely to remain abstinent at 12-month follow-up. When assessing the association using continuous abstinence measures, the standardised OR for abstinence was non-significant at 1.10. One reference examined gender with a follow-up greater than 12 months using both point-prevalence and continuous abstinence measures and did not report a significant relationship or provide data beyond significance.

Two references assessed the association between age and sustained abstinence at 6- to 12-month follow-up, both using point-prevalence measures of abstinence. One reference was considered at low risk of bias, and one at moderate risk. The median OR for sustained abstinence was 1.84 (range: 1.0–2.64) for older age. One reference reported a significant association (Thorndike et al., 2016). One reference examined age with a follow-up greater than 12 months using both point-prevalence and continuous abstinence measures and did not report a significant relationship or provide data beyond significance.

Clinical characteristics

Six references compared the use of typical and atypical antipsychotic medication as a factor associated with sustained abstinence. One reference, assessed as at moderate risk of bias, used point-prevalence measures of abstinence at 3-month follow-up and found no significant relationship. Three references examined the relationship at a 6- to 12-month follow-up, all using point-prevalence measures of abstinence. One reference was considered at moderate risk of bias and two at high risk. The median OR for sustained abstinence was 1.77 (range: 1.04–2.55) for atypical compared to typical antipsychotic medication, and one reference reported a significant relationship (George et al., 2000). Two references examined the association with sustained abstinence at a follow-up greater than 12 months, one used point-prevalence measures of abstinence and one used both point-prevalence and continuous abstinence measures. Neither reported a significant relationship or provided data beyond significance. Of these, one was assessed as moderate risk of bias and one at high risk.

The relationship between psychiatric diagnosis and sustained abstinence was examined in four references. Three references assessed the relationship at a 6- to 12-month follow-up, and all used point-prevalence measures of abstinence. The median OR for sustained abstinence was 1.45 (range: 0.86–1.85) for schizophrenia and schizoaffective disorder diagnoses compared to other psychotic disorders and none reported a significant association. One reference was considered at low risk of bias, one at moderate risk and one at high risk. One reference examined the relationship between diagnosis and sustained abstinence at a follow-up greater than 12 months, using both point-prevalence and continuous measures of abstinence. This reference was considered at moderate risk of bias and did not report a significant relationship.

Two references looked at the association between psychosis symptoms and sustained abstinence, one with a follow-up at 6–12 months, and one with a follow-up greater than 12 months. Both used point-prevalence measures of abstinence and neither reported a significant relationship.

The association between physical health variables and sustained abstinence was measured only at 6–12 months and by one reference (Thorndike et al., 2016). A significant association with sustained abstinence was reported for hyperlipidaemia (Mdn = −4.9 vs Mdn = −1.0), with a greater number of those in the sustained abstinence group reporting hyperlipidaemia at baseline. Remaining abstinent was also found to be significantly associated with reduced cardiovascular disease risk and an increase in weight; however, these were likely to be outcomes from the intervention rather than predictors. The reference was considered at moderate risk of bias.

Two references examined the relationship between functioning and sustained abstinence. One examined the relationship at a 6- to 12-month follow-up using point-prevalence measures of abstinence, and one at a follow-up greater than 12 months using both point-prevalence and continuous abstinence measures. Neither reported a significant relationship.

The relationship between substance use and sustained abstinence was assessed by one reference at a follow-up greater than 12 months using both point-prevalence and continuous measures of abstinence. The reference was considered at moderate risk of bias and did not report a significant effect.

Smoking history

Four references examined the relationship between baseline smoking characteristics (e.g. heaviness of smoking, nicotine dependency, number of daily cigarettes) and sustained abstinence. Two references looked at the relationship at a 6- to 12-month follow-up using point-prevalence measures of abstinence. One was considered at low risk of bias and one at moderate risk. Neither reference reported a significant association for any of the variables.

Two references examined the association between baseline smoking factors and sustained abstinence at a follow-up greater than 12 months. One reference examined the association of five different variables with sustained abstinence using point-prevalence and continuous abstinence measures and reported no significant relationships. The reference did not provide any data beyond significance and was considered at moderate risk of bias. One reference, assessed as high risk of bias, reported a significant association between smoking reduction in a previous trial and sustained abstinence at a 2-year follow-up using point-prevalence measures (Evins et al., 2004).

Factors associated with relapse

Only one study looked at factors associated with relapse to smoking (Horst et al., 2005), reporting that the group assigned to nicotine replacement therapy (NRT) were significantly less likely to relapse into smoking than the placebo group (33.3% vs 100%). No other factors were examined.

Risk of bias in included studies

Risk of bias assessments are summarised in Tables 5 and 6. Twenty references (reporting on 17 RCT studies) were evaluated for risk of bias using the RoB 2.0 tool. Three references reporting on non-RCT studies (Addington et al., 1998; Cather et al., 2013; Garcia-Portilla et al., 2016) were evaluated using the ROBINS-I tool (Sterne et al., 2016). For those references assessed using the RoB 2.0 tool (Table 5), the majority of studies were assessed as ‘some concerns’. Four references were considered low risk across all domains, and three references had at least one domain rated as high risk. The predominant reason for assessments noted as ‘some concerns’ was lack of available analysis plan. One study (Gilbody et al., 2015) was rated as ‘some concerns’ and one ‘high risk’ (Rogers et al., 2017) on the ‘measurement of outcome’, due to reliance in part or fully on self-report measures of abstinence. For those references assessed by the ROBINS-I tool (Table 6), all three were considered to be at serious risk of bias. This was largely due to ‘bias due to confounding’, for example, not controlling for confounding variables such as severity of mental illness or smoking history. Decisions on risk of bias assessments can be found in Supplementary 3.

Table 5.

Risk of bias assessments (RoB 2.0).

Author	Randomisation process	Intervention deviations	Missing outcome data	Outcome measurement	Selection of reported result	Overall risk of bias
Baker et al. (2006) ^a	Low	Low	Low	Low	Some concerns	Some concerns
Baker et al. (2010)	Low	Low	Low	Low	Some concerns	Some concerns
Baker et al. (2015) ^b	Low	Low	Low	Low	Low	Low
Baker et al. (2018)	Low	Low	Low	Low	Low	Low
Chengappa et al. (2014)	Low	Low	Low	Low	Some concerns	Some concerns
Evins et al. (2001)	Low	Low	Low	Low	Some concerns	Some concerns
Evins et al. (2004)	Low	High	Low	Low	Some concerns	High
Evins et al. (2005)	Low	Low	Low	Low	Some concerns	Some concerns
Evins et al. (2007)	Low	Low	Low	Low	Some concerns	Some concerns
Evins et al. (2014) ^c	Low	Low	Low	Low	Some concerns	Some concerns
George et al. (2000)	High	Low	Low	Low	Some concerns	High
George et al. (2002)	Low	Low	Low	Low	Some concerns	Some concerns
George et al. (2008)	Low	Low	Low	Low	Some concerns	Some concerns
Gilbody et al. (2015)	Low	Low	Low	Some concerns	Some concerns	Some concerns
Gilbody et al. (2019)	Low	Low	Low	Low	Low	Low
Horst et al. (2005)	Low	Low	Low	Low	Some concerns	Some concerns
Jaen-Moreno et al. (2021)	Low	Low	Low	Low	Low	Low
Rogers et al. (2017)	Low	Low	Low	High	Some concerns	High
Williams et al. (2010)	Low	Low	Low	Low	Some concerns	Some concerns
Williams et al. (2012)	Low	Low	Low	Low	Some concerns	Some concerns

Filia et al. (2014) conducted a secondary analysis of the study by Baker et al. (2006) on the same outcome time point.

Clark et al. (2017) conducted a secondary analysis of the study by Baker et al. (2015) on the same outcome time point.

Thorndike et al. (2016) conducted a secondary analysis of the study by Evins et al. (2014) on the same outcome time point.

Table 6.

Risk of bias assessments (ROBINS-I).

Criteria	Addington et al. (1998)	Cather et al. (2013)	Garcia-Portilla et al. (2016)
Bias due to confounding	Serious	Serious	Serious
Bias in selection of participants	Low	Low	Low
Bias in classification of interventions	Low	Low	Low
Bias due to deviations from intended intervention	Low	Low	Serious
Bias due to missing data	Moderate	Moderate	Moderate
Bias in measurement of outcomes	Low	Low	Low
Bias in selection of the reported result	Moderate	Moderate	Moderate
Overall	Serious	Serious	Serious

Meta-analysis of effect of intervention

Point-prevalence abstinence overall

The aggregated estimate for point-prevalence abstinence was 1.49 (95% CI = [1.05, 2.11], p = 0.03), indicating an overall 49% higher odds for the intervention groups to show abstinence at follow-up compared to control groups (Figure 2). Heterogeneity was low to moderate (I² = 34.9%, Q = 26.42, df = 17, p = 0.07). There was evidence of asymmetry, indicating possible publication bias. So, the overall effect size was re-estimated as OR = 1.38 (95% CI = [0.92, 2.10]).

Figure 2.

Overall effect of any intervention versus no intervention measured via point-prevalence abstinence.

Point-prevalence abstinence by follow-up time

Only one reference had a follow-up time of less than 6 months. This was collapsed into the 6–12 months category, thus the analysis was run on only two subgroups. For the less than or equal to 12 months subgroup, the aggregated estimate for abstinence was 1.69 (95% CI = [1.12, 2.56]), indicating an overall 69% higher odds for intervention groups to show abstinence at follow-up within 12 months compared to control groups (p = 0.06). For the greater than 12 months subgroup, the aggregated estimate for abstinence was 0.95 (95% CI = [0.53, 2.11], p = 0.54; Figure 3).

Figure 3.

Point-prevalence abstinence by follow-up time.

Continuous abstinence

As there were only five references included, no subgroup analyses were performed. The estimated OR = 1.60 (95% CI = [0.67, 3.83], p = 0.29) showed higher odds in the intervention groups for continuous abstinence relative to control groups, but the CI was wide. There was no evidence of asymmetry, though with only five studies this is difficult to demonstrate (Supplementary 4).

Discussion

Summary of findings

To our knowledge, this is the first study to systematically review the literature examining the factors associated with sustained abstinence in people experiencing SMI following a smoking cessation intervention. The key finding was that participation in smoking cessation and relapse prevention interventions in general was associated with higher odds of abstinence in medium-term follow-ups compared to control groups. This finding was of borderline significance at up to 12-month follow-up, but the effect was no longer demonstrable at follow-ups greater than 12 months. There was a lack of information on the effect of other factors associated with abstinence in the short, medium and long term, largely due to their being rarely measured beyond the end of smoking cessation studies. Despite increased interest in investigating smoking cessation interventions in people with SMI, there was a lack of well-designed studies of sufficient sample size that investigate the important question of what factors predict sustained abstinence following successful quitting.

The majority of references included in the review explored the association between intervention and abstinence. The finding that participation in an intervention overall increased the odds of sustained abstinence at follow-up, compared to control groups, suggests the interventions do have a positive impact on sustained abstinence in this population. However, this finding may be skewed by the much higher odds reported by two relapse prevention studies, which provided more intense support for a longer duration. Furthermore, the heterogeneity in study and intervention types included in this review meant that more detailed analyses to establish whether particular interventions were associated with greater effects could not be conducted.

In short-term follow-ups (i.e. <6 months) only therapeutic relationship was reported as a significant factor in predicting sustained abstinence, however, this was measured by just one reference and was at moderate risk of bias. Most references measured the effect of potential predictors of abstinence over the medium term (i.e. 6–12 months), with the effect of intervention most commonly examined, followed by programme attendance. There was limited measurement of participant characteristics such as demographic background, psychiatric diagnosis or smoking behaviours when commencing the intervention. Factors associated with abstinence over long-term follow-up (i.e. >12 months) were rarely measured, and only smoking reduction in one previous trial was reported to have a significant relationship. However, the sample size was small and the study was considered at high risk of bias due to participants in the placebo group taking the study drug during the follow-up period.

Abstinence rates in the included studies varied widely depending on the length of follow-up and whether abstinence was assessed via point-prevalence or continuous abstinence measures. Point-prevalence estimates ranged between 6.6% and 45.0% at longest follow-up, while continuous abstinence measures revealed more conservative estimates of 5.4–19.0% at 6-month follow-up and 3.9–14.3% at 12-month follow-up. Although this is only reflective of the included references, and prevalence rates may differ in the broader smoking literature on people experiencing SMI, it highlights the relatively low sustained abstinence rates in this group. While direct comparisons cannot be drawn, general population estimates report a smaller and higher range of 25–50% point-prevalence of abstinence in the 12 months following a quit date (Ferguson et al., 2005; García-Rodríguez et al., 2013), depending on the intervention, length of follow-up and method used for determining abstinence.

Session attendance was examined by seven references and significantly associated with abstinence outcomes in three. Since the study interventions differed in length and intervention type, direct comparisons could not be drawn and an ideal attendance rate could not be concluded. Similarly, therapeutic relationship was related to abstinence in one study (Williams et al., 2010). These findings suggest that participant engagement may be an important factor for success; however, the small number of references examining these factors meant the evidence of an effect could not be determined.

There was limited evidence for a relationship between participant characteristics and smoking abstinence. Only one of three references found an association with age, in which participants in the abstinent group were older (Thorndike et al., 2016) and one of four references found a significant association with gender (Clark et al., 2017). Female participants were found to report a higher likelihood of sustained abstinence than their male peers, in contrast to the broader research on smoking cessation in which women reportedly face greater difficulties in maintaining long-term abstinence (Smith et al., 2016). Sampling bias may contribute to this finding, as a higher proportion of participants were male.

Only one reference of the six, which examined antipsychotic medication as a correlate, found a significant effect. Those prescribed an atypical antipsychotic were more than twice as likely to report abstinence at follow-up than those on typical antipsychotics (George et al., 2000). Other references, which examined mental health diagnosis and type of antipsychotic prescribed, found no significant relationship to smoking abstinence. Given that the inclusion criteria required participant samples to primarily comprise people experiencing a psychotic disorder, and that none of the references directly compared to a general population sample, it is likely that the homogeneity in diagnosis prevented any meaningful association with sustained abstinence being detected. The inclusion of people experiencing SMI in large RCTs would provide further information on the effect that mental health diagnosis may have on long-term abstinence outcomes in relation to the general population (Talukder et al., 2021).

Despite people experiencing SMI reporting heavier smoking and greater nicotine dependence than the general population, smoking characteristics at baseline were not related to sustained abstinence in the four references that were examined for this, suggesting that they may not be contributing factors to the lower success and abstinence rates in this group. Alternatively, this may reflect that quitting smoking is equally difficult regardless of smoking heaviness and dependence, or that there is not enough range in the variable to show a correlation with the outcome (abstinence) due to all participants scoring highly.

Finally, evidence for the role of physical health factors in smoking abstinence outcomes was limited to a single reference (Thorndike et al., 2016). Following a varenicline intervention, participants in the abstinent group reported higher rates of cardiometabolic issues than those who relapsed to smoking. This may suggest that poorer physical health acted as a motivating factor for continued abstinence, in line with findings from the general population in which ‘health concerns’ are often cited as a reason for smoking cessation (McCaul et al., 2006).

A number of factors commonly reported as being associated with smoking abstinence and/or smoking relapse in the general population were not measured in the studies included in this review. For instance, education, substance use, financial reasons, smoking status of social and household contacts, family and peer support to quit and social consequences of smoking (e.g. others dislike scent; Lee and Kahende, 2007; Murray et al., 2000). These may have provided a more comprehensive picture of the factors involved in successfully maintaining abstinence in people experiencing SMI and whether these differ from those seen in the general population.

Methodological considerations

Criteria for inclusion in this review required a minimum of 3-month follow-up to measure abstinence (point-prevalence or continuous abstinence), shorter than the Cochrane accepted and Russell Standard’s recommended 6 months (West et al., 2005). Given the scarcity of studies in this population and the well-documented rates of relapse, the shorter period was chosen to broaden the number of studies captured and increase the likelihood of a period of abstinence being reported. The majority of references measured abstinence outcomes via objective means, with all except two (Addington et al., 1998; Rogers et al., 2017) utilising CO monitoring in keeping with best practice in cessation trials. However, the definition of abstinence and cut-off for CO readings varied and the preferred standard of measuring abstinence – defined as continuous abstinence for 3 months or more – was met by only six references. A consistent approach to defining abstinence, as outlined in the Russell Standard, would improve comparability between studies and bring clarity to the interpretation of their effectiveness (West et al., 2005). Furthermore, inclusion in the review required study samples to have at least 75% of participants experiencing a psychotic disorder, or that the data required for extraction to be reported separately for people with a psychotic disorder, resulting in well-known studies such as the EAGLES study (Anthenelli et al., 2016) being excluded.

Finally, a number of the studies included were designed to primarily address the safety of pharmacological therapies and to assess their impact on psychiatric symptoms. This, in addition to high dropout rates, resulted in small sample sizes that are potentially underpowered to detect any meaningful effect of the interventions on sustained abstinence or factors associated with abstinence.

Strengths and limitations

All studies included in this review were investigating smoking abstinence via an intervention and their eligibility criteria required that participants were interested in smoking cessation. This increases the likelihood that the abstinence rates reported, and any factors associated with them, are representative of people experiencing SMI who are motivated to cease smoking. In addition, the inclusion criteria for this review focused only on people with psychotic conditions, therefore findings may not be generalisable to other mental illnesses that are often grouped under the term SMI (e.g. posttraumatic stress disorder [PTSD], severe depression).

The exclusion of studies that examined enforced smoking cessation, for instance, during hospital stays, may have inadvertently limited the review to studies that only encompass participants living in the community. Furthermore, since this review aimed to examine factors associated with smoking abstinence, studies investigating the impact of interventions on smoking reduction were excluded. While complete abstinence is most desirable given the health benefits of doing so, a reduction in smoking and nicotine consumption may also warrant investigation as this may be a more achievable real-world goal. Future research may examine factors associated with smoking reduction and draw comparisons with those associated with abstinence to identify where additional supports may be needed to move people towards abstinence. A better understanding of the potential benefit of e-cigarettes and novel approaches such as tailored text messaging support (Boland et al., 2018) warrants exploration in the SMI population (Kock et al., 2019).

Finally, a meta-analysis was completed to examine the overall effect of receiving an intervention on sustained abstinence, compared to no intervention; however, the variation across included references in study design, type of intervention delivered and measurement of abstinence, in addition to the limited data available meant that more complex analyses could not be conducted for individual factors. Furthermore, we had planned to conduct subgroup analyses by intervention type, however, this was not possible due to variance within types (e.g. behavioural interventions encompassed a range of approaches) and were often combined meaning the effects of each could not be separated). Where more data are available in the future, further research may employ more sophisticated methods to further develop knowledge in this area.

Recommendations

While much of the research into smoking cessation in people experiencing SMI has focused on developing interventions to support quitting, a greater focus on supporting long-term abstinence is much needed. None of the included studies explicitly examined predictors of sustained abstinence and most only examined intervention as a correlate with abstinence outcomes. Future research could focus on identifying the specific factors that contribute to ongoing abstinence in people experiencing SMI, which may aid in the design of more effective interventions. Co-designing smoking cessation interventions with people experiencing SMI who smoke may also assist in ensuring interventions meet these specific needs and are appropriate in their demands on participants.

More high-quality research is needed to determine the long-term effectiveness of pharmacological treatments such as varenicline, bupropion and NRT on smoking cessation in people experiencing SMI. While such medications appear to aid in initial smoking cessation attempts, to date there is limited evidence on their long-term benefits in people experiencing SMI, how they can be used to promote sustained abstinence and whether any adverse events may be associated with prolonged use in this population.

Conclusion

Future research should aim to better understand how abstinence can be maintained following a smoking cessation attempt among people experiencing SMI. Further assessment of the effectiveness of interventions designed to promote ongoing cessation and prevention of relapse among larger sample sizes is needed, with a particular focus on identifying predictors of long-term abstinence in this population. High-quality research that minimises risk of bias is needed to enable better understanding of this important question.

Supplemental Material

sj-docx-1-anp-10.1177_00048674221147206 – Supplemental material for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention

Supplemental material, sj-docx-1-anp-10.1177_00048674221147206 for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention by Kimberley Davies, Ryan J Courtney, Miranda Summersby-Mitchell, Rachel Morell, Nancy Briggs and Julia M Lappin in Australian & New Zealand Journal of Psychiatry

Supplemental Material

sj-docx-2-anp-10.1177_00048674221147206 – Supplemental material for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention

Supplemental material, sj-docx-2-anp-10.1177_00048674221147206 for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention by Kimberley Davies, Ryan J Courtney, Miranda Summersby-Mitchell, Rachel Morell, Nancy Briggs and Julia M Lappin in Australian & New Zealand Journal of Psychiatry

Supplemental Material

sj-docx-3-anp-10.1177_00048674221147206 – Supplemental material for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention

Supplemental material, sj-docx-3-anp-10.1177_00048674221147206 for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention by Kimberley Davies, Ryan J Courtney, Miranda Summersby-Mitchell, Rachel Morell, Nancy Briggs and Julia M Lappin in Australian & New Zealand Journal of Psychiatry

Supplemental Material

sj-docx-4-anp-10.1177_00048674221147206 – Supplemental material for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention

Supplemental material, sj-docx-4-anp-10.1177_00048674221147206 for A systematic review of factors associated with sustained smoking abstinence in people experiencing severe mental illness following participation in a smoking intervention by Kimberley Davies, Ryan J Courtney, Miranda Summersby-Mitchell, Rachel Morell, Nancy Briggs and Julia M Lappin in Australian & New Zealand Journal of Psychiatry

Footnotes

Acknowledgements

This research was supported by the National Drug and Alcohol Centre (University of New South Wales), which is supported by funding from the Australian Government.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This research was funded by a Career Development Fellowship (grant no. 1148497; awarded to Dr Courtney) from the Australian National Health and Medical Research Council.

ORCID iD

Kimberley Davies

Supplemental material

Supplemental material for this article is available online.

References

Addington

el-Guebaly

Campbell

, et al. (1998) Smoking cessation treatment for patients with schizophrenia. The American Journal of Psychiatry 155: 974–975.

Anthenelli

Benowitz

West

, et al. (2016) Neuropsychiatric safety and efficacy of varenicline, bupropion, and nicotine patch in smokers with and without psychiatric disorders (EAGLES): A double-blind, randomised, placebo-controlled clinical trial. The Lancet 387: 2507–2520.

Aschbrenner

Brunette

McElvery

, et al. (2015) Cigarette smoking and interest in quitting among overweight and obese adults with serious mental illness enrolled in a fitness intervention. The Journal of Nervous and Mental Disease 203: 473–476.

Baker

Richmond

Haile

, et al. (2006) A randomized controlled trial of a smoking cessation intervention among people with a psychotic disorder. The American Journal of Psychiatry 163: 1934–1942.

Baker

Richmond

Lewin

, et al. (2010) Cigarette smoking and psychosis: Naturalistic follow up 4 years after an intervention trial. Australian and New Zealand Journal of Psychiatry 44: 342–350.

Baker

Richmond

Kay-Lambkin

, et al. (2018) Randomised controlled trial of a healthy lifestyle intervention among smokers with psychotic disorders: Outcomes to 36 months. Australian and New Zealand Journal of Psychiatry 52: 239–252.

Baker

Richmond

Kay-Lambkin

, et al. (2015) Randomized controlled trial of a healthy lifestyle intervention among smokers with psychotic disorders. Nicotine & Tobacco Research 17: 946–954.

Boland

Stockings

Mattick

, et al. (2018) The methodological quality and effectiveness of technology-based smoking cessation interventions for disadvantaged groups: A systematic review and meta-analysis. Nicotine & Tobacco Research 20: 276–285.

Bowden

Miller

Hiller

(2011) Smoking and mental illness: A population study in South Australia. Australian and New Zealand Journal of Psychiatry 45: 325–331.

10.

Brown

Kim

Mitchell

, et al. (2010) Twenty-five year mortality of a community cohort with schizophrenia. The British Journal of Psychiatry 196: 116–121.

11.

Bucklin

(2021). A 5-factor framework for assessing tobacco use disorder. Tobacco Use Insights. Epub ahead of print 26 February 2021. DOI: 10.1177/1179173X21998355.

12.

Cather

Dyer

Burrell

, et al. (2013) An open trial of relapse prevention therapy for smokers with schizophrenia. Journal of Dual Diagnosis 9: 87–93.

13.

Chengappa

Perkins

Brar

, et al. (2014) Varenicline for smoking cessation in bipolar disorder: A randomized, double-blind, placebo-controlled study. The Journal of Clinical Psychiatry 75: 765–772.

14.

Clark

Baker

Lewin

, et al. (2017) Self-reported reasons for smoking: Predicting abstinence and implications for smoking cessation treatments among those with a psychotic disorder. Journal of Dual Diagnosis 13: 6–14.

15.

Dickerson

Schroeder

Katsafanas

, et al. (2018) Cigarette smoking by patients with serious mental illness, 1999–2016: An increasing disparity. Psychiatric Services 69: 147–153.

16.

Evins

Cather

Culhane

, et al. (2007) A 12-week double-blind, placebo-controlled study of bupropion SR added to high-dose dual nicotine replacement therapy for smoking cessation or reduction in schizophrenia. Journal of Clinical Psychopharmacology 27: 380–386.

17.

Evins

Cather

Deckersbach

, et al. (2005) A double-blind placebo-controlled trial of bupropion sustained-release for smoking cessation in schizophrenia. Journal of Clinical Psychopharmacology 25: 218–225.

18.

Evins

Cather

Pratt

, et al. (2014) Maintenance treatment with varenicline for smoking cessation in patients with schizophrenia and bipolar disorder: A randomized clinical trial. Journal of the American Medical Association 311: 145–154.

19.

Evins

Mays

Rigotti

, et al. (2001) A pilot trial of bupropion added to cognitive behavioral therapy for smoking cessation in schizophrenia. Nicotine & Tobacco Research 3: 397–403.

20.

Ferguson

Bauld

Chesterman

, et al. (2005) The English smoking treatment services: One-year outcomes. Addiction 100: 59–69.

21.

Filia

Baker

Gurvich

, et al. (2014) Gender differences in characteristics and outcomes of smokers diagnosed with psychosis participating in a smoking cessation intervention. Psychiatry Research 215: 586–593.

22.

Garcia-Portilla

Garcia-Alvarez

Sarramea

, et al. (2016) It is feasible and effective to help patients with severe mental disorders to quit smoking: An ecological pragmatic clinical trial with transdermal nicotine patches and varenicline. Schizophrenia Research 176: 272–280.

23.

García-Rodríguez

Secades-Villa

Flórez-Salamanca

, et al. (2013) Probability and predictors of relapse to smoking: Results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug and Alcohol Dependence 132: 479–485.

24.

George

Vessicchio

Sacco

, et al. (2008) A placebo-controlled trial of bupropion combined with nicotine patch for smoking cessation in schizophrenia. Biological Psychiatry 63: 1092–1096.

25.

George

Vessicchio

Termine

, et al. (2002) A placebo controlled trial of bupropion for smoking cessation in schizophrenia. Biological Psychiatry 52: 53–61.

26.

George

Ziedonis

Feingold

, et al. (2000) Nicotine transdermal patch and atypical antipsychotic medications for smoking cessation in schizophrenia. The American Journal of Psychiatry 157: 1835–1842.

27.

Gilbody

Peckham

Bailey

, et al. (2019) Smoking cessation for people with severe mental illness (SCIMITAR+): A pragmatic randomised controlled trial. The Lancet Psychiatry 6: 379–390.

28.

Gilbody

Peckham

Man

, et al. (2015) Bespoke smoking cessation for people with severe mental ill health (SCIMITAR): A pilot randomised controlled trial. The Lancet Psychiatry 2: 395–402.

29.

Greenhalgh

Brennan

Segan

, et al. (2022) Monitoring changes in smoking and quitting behaviours among Australians with and without mental illness over 15 years. Australian and New Zealand Journal of Public Health 46: 223–229.

30.

Henmi

Copas

(2010) Confidence intervals for random effects meta-analysis and robustness to publication bias. Statistics in Medicine 29(29): 2969–2983.

31.

Hjorthøj

Stürup

McGrath

, et al. (2017) Years of potential life lost and life expectancy in schizophrenia: A systematic review and meta-analysis. The Lancet Psychiatry 4: 295–301.

32.

Horst

Klein

Williams

, et al. (2005) Extended use of nicotine replacement therapy to maintain smoking cessation in persons with schizophrenia. Neuropsychiatric Disease and Treatment 1: 349–355.

33.

Jaen-Moreno

Feu

Del Pozo

, et al. (2021) Chronic obstructive pulmonary disease in severe mental illness: A timely diagnosis to advance the process of quitting smoking. European Psychiatry 64: e22.

34.

Kock

Brown

Hiscock

, et al. (2019) Individual-level behavioural smoking cessation interventions tailored for disadvantaged socioeconomic position: A systematic review and meta-regression. The Lancet Public Health 4: e628–e644.

35.

Lappin

Wijaya

Watkins

, et al. (2018) Cardio-metabolic risk and its management in a cohort of clozapine-treated outpatients. Schizophrenia Research 199: 367–373.

36.

Lawrence

Mitrou

Zubrick

(2009) Smoking and mental illness: Results from population surveys in Australia and the United States. BMC Public Health 9: 285.

37.

Lee

Kahende

(2007) Factors associated with successful smoking cessation in the United States, 2000. American Journal of Public Health 97: 1503–1509.

38.

Lum

Skelton

Wynne

, et al. (2018) A systematic review of psychosocial barriers and facilitators to smoking cessation in people living with schizophrenia. Frontiers in Psychiatry 9: 565.

39.

McCaul

Hockemeyer

Johnson

, et al. (2006) Motivation to quit using cigarettes: A review. Addictive Behaviors 31: 42–56.

40.

McClave

McKnight-Eily

Davis

, et al. (2010) Smoking characteristics of adults with selected lifetime mental illnesses: Results from the 2007 National Health Interview Survey. American Journal of Public Health 100: 2464–2472.

41.

McKenzie

Brennan

(2022) Chapter 12: Synthesizing and presenting findings using other methods. In: Higgins

JPT

Thomas

Chandler

, et al. (eds) Cochrane Handbook for Systematic Reviews of Interventions Version 6.3 (Updated February 2022). Available at: https://training.cochrane.org/handbook/current/chapter-12

42.

Morisano

Wing

Sacco

, et al. (2013) Effects of tobacco smoking on neuropsychological function in schizophrenia in comparison to other psychiatric disorders and non-psychiatric controls. The American Journal on Addictions 22: 46–53.

43.

Murray

Gerald

Lindgren

, et al. (2000) Characteristics of participants who stop smoking and sustain abstinence for 1 and 5 years in the lung health study. Preventive Medicine 30: 392–400.

44.

Rogers

Friedes

Jakes

, et al. (2017) Long-term abstinence and predictors of tobacco treatment uptake among hospitalized smokers with serious mental illness enrolled in a smoking cessation trial. Journal of Behavioral Medicine 40: 750–759.

45.

Smith

Bessette

Weinberger

, et al. (2016) Sex/gender differences in smoking cessation: A review. Preventive Medicine 92: 135–140.

46.

Sterne

JAC

Hernán

Reeves

, et al. (2016) ROBINS-I: A tool for assessing risk of bias in non-randomised studies of interventions. British Medical Journal 355: i4919.

47.

Strand

Nybäck

(2005) Tobacco use in schizophrenia: A study of cotinine concentrations in the saliva of patients and controls. European Psychiatry 20: 50–54.

48.

Sweeney

Air

Zannettino

, et al. (2015) Psychosis, socioeconomic disadvantage, and health service use in South Australia: Findings from the second Australian national survey of psychosis. Frontiers in Public Health 3: 259.

49.

Talukder

Lappin

Boland

, et al. (2021) Inequity in smoking cessation clinical trials testing pharmacotherapies: Exclusion of smokers with mental health disorders. Tobacco Control. Epub ahead of print 2 December. DOI: 10.1136/tobaccocontrol-2021-056843.

50.

Taylor

GMJ

Lindson

Farley

, et al. (2021) Smoking cessation for improving mental health. Cochrane Database of Systematic Reviews 3: CD013522.

51.

Thorndike

Achtyes

Cather

, et al. (2016) Weight gain and 10-year cardiovascular risk with sustained tobacco abstinence in smokers with serious mental illness: A subgroup analysis of a randomized trial. The Journal of Clinical Psychiatry 77: e320–e326.

52.

Tidey

Miller

(2015) Smoking cessation and reduction in people with chronic mental illness. British Medical Journal 351: h4065.

53.

Tsoi

Porwal

Webster

(2013) Interventions for smoking cessation and reduction in individuals with schizophrenia. Cochrane Database of Systematic Reviews 2013: CD007253.

54.

West

Hajek

Stead

, et al. (2005) Outcome criteria in smoking cessation trials: Proposal for a common standard. Addiction 100: 299–303.

55.

Williams

Anthenelli

Morris

, et al. (2012) A randomized, double-blind, placebo-controlled study evaluating the safety and efficacy of varenicline for smoking cessation in patients with schizophrenia or schizoaffective disorder. The Journal of Clinical Psychiatry 73: 654–660.

56.

Williams

Steinberg

Zimmermann

, et al. (2010) Comparison of two intensities of tobacco dependence counseling in schizophrenia and schizoaffective disorder. Journal of Substance Abuse Treatment 38: 384–393.

57.

Williams

Ziedonis

Abanyie

, et al. (2005) Increased nicotine and cotinine levels in smokers with schizophrenia and schizoaffective disorder is not a metabolic effect. Schizophrenia Research 79: 323–335.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

0.03 MB

0.05 MB

0.04 MB