Preoperative sense of coherence associated with the 10-year outcomes of lumbar spinal stenosis surgery

Abstract

A prospective 10-year follow-up study was conducted to determine the significance of the preoperative sense of coherence, with respect to the preoperative and 10-year clinical characteristics, among lumbar spinal stenosis patients (N = 99). In addition, the predictive value of the preoperative sense of coherence regarding the 10-year surgery outcome was also evaluated. In a logistic regression analysis, a weak preoperative sense of coherence and low functional ability predicted the patients’ functional ability 10 years after the surgery. Moreover, those patients with weak sense of coherence before surgery showed poorer functional ability 10 years after the surgery, but not preoperatively. A weak preoperative sense of coherence seems to associate with poorer long-term outcome after surgery; therefore, various rehabilitation strategies are discussed.

Keywords

follow-up functional ability lumbar spinal stenosis sense of coherence surgery

Introduction

Lumbar spinal stenosis (LSS), which is a narrowing of the spinal canal, causes intermittent low-back pain and radiculopathy when symptomatic (Arnoldi et al., 1976; Verbiest, 1954). Albeit not life-threatening, it is a painful and disabling condition, and an increasingly common diagnosis, particularly among the ageing population. The most common form of degenerative stenosis generally becomes symptomatic during or after the seventh decade of life (Paine, 1976). The symptoms of LSS are usually relieved with nonsurgical management (Theodoridis et al., 2008), but surgical treatment is indicated for those patients with severe pain or constant neurological symptoms and in cases where conservative treatment fails (Onel et al., 1993). Previous research has shown that the initial surgical treatment provided greater improvement in the LSS symptoms than the initial nonsurgical treatment over a 10-year follow-up (Chang et al., 2005). However, due to the naturally occurring degenerative processes of the spine, the benefits of the surgical treatment diminish over time (Atlas et al., 2005; Chang et al., 2005).

In addition to the pathophysiological and degenerative spinal processes, psychological factors, such as depression (Pakarinen et al., 2014; Sinikallio et al., 2011a), coping resources (Higuchi, 2016) and pain catastrophizing (Coronado et al., 2015), have been found to affect the postoperative recovery and surgery outcomes among LSS patients (see also Celestin et al., 2009).Sense of coherence (SOC) (Antonovsky, 1981, 1993) is a psychological construct that has been shown to be significantly associated with a wide variety of health outcomes, including the perceived health status, mental health (Eriksson and Lindström, 2006; Flensborg-Madsen et al., 2005) and musculoskeletal rehabilitation outcomes (Benz et al., 2013; Lydell et al., 2011). Stemming from Antonovsky’s (1981, 1993) health promoting theory SOC is a compilation of protective resources, since it consists of three components (comprehensibility, manageability and meaningfulness) that help the individual buffer adverse mental and physical health challenges, and cope better, with lesser stress (Eriksson and Lindström, 2006; Flensborg-Madsen et al., 2005; Lutgendorf et al., 1999).

It has been previously shown that the postoperative recovery of LSS patients in a weak SOC group was halted from the 3-month to 1-year follow-ups (Sinikallio et al., 2011b), and that a weak SOC during a 3-month follow-up predicted poorer surgery outcomes in the 5-year follow-up (Pakarinen et al., 2017). However, no previous studies have been found on the significance of the preoperative SOC with respect to LSS patients’ long-term (10 years) surgery outcomes. Therefore, long-term follow-up studies are needed to untangle those factors related to the postoperative function and well-being of LSS patients, extending past the immediate and short-term postoperative recovery and rehabilitation phases. Consequently, the aims of this study were to (1) study the significance of preoperative SOC with respect to the baseline and 10-year clinical characteristics among LSS patients and (2) study the predictive value of the preoperative SOC regarding the 10-year LSS surgery outcomes.

Methods

Study design

This was a prospective clinical follow-up study including an enhanced physiotherapeutic rehabilitation intervention for half of the participants at the 3-month follow-up phase. The study population consisted of patients with radiologically and clinically defined LSS who underwent decompressive surgery. The surgery selection was carried out by an orthopaedist or a neurosurgeon at Kuopio University Hospital in Finland between October 2001 and October 2004.

The study design was approved by the Ethics Committees of the University of Kuopio and Kuopio University Hospital. The criteria for inclusion in this study (i.e. for operative treatment) were the presence of (1) severe pain in the back, buttocks and/or lower extremities, (2) radiographic evidence of compression of the cauda equina or degenerative changes in the nerve roots and (3) a surgeon’s clinical evaluation of degenerative LSS requiring operative treatment. All of the participants had histories of insufficient responses to conservative treatment. The exclusion criteria were as follows: emergency or urgent spinal surgery precluding recruitment and protocol investigations, cognitive impairment prohibiting completion of the questionnaires or other failures in co-operation and the presence of metallic particles in the body preventing a magnetic resonance imaging (MRI) investigation.

All of the participants received routine preoperative information at the hospital regarding immediate postoperative mobilization, in which they were advised to remain active and carry on with their normal daily living without restrictions. The participants had routine follow-up visits with the orthopaedic or neurosurgical clinics 2–3 months postoperatively, at which point the surgeon confirmed that there were no restrictions to rehabilitation. Those participants randomized to the enhanced rehabilitation intervention received a supervised training session (i.e. stretching and strengthening exercises) once a week, lasting 12 weeks, and it was repeated 12 months postoperatively. Other possible postoperative treatments (e.g. analgesics, other types of physiotherapy) prescribed by a treating surgeon/general practitioner were not prohibited. The enhanced rehabilitation intervention did not have any effect on the surgical outcome at the 2-year follow-up (Aalto et al., 2011).

In total, 102 participants provided informed consent during their baseline outpatient visits to the Department of Physical and Rehabilitation Medicine and were included in this study. At the 10-year follow-up, 72 also responded to the study questionnaires. In all, 17 of the baseline participants had died, 1 could not be contacted, 10 refused to participate and 2 could not complete the 10-year questionnaire. In this study, only those participants’ data with complete SOC scores were analysed; therefore, the number of participants was 99 at the baseline and 69 at the 10-year follow-up.

Questionnaires

The participants completed a study questionnaire at the baseline and at the 10-year follow-up; they received and returned the study questionnaire to the Department of Physical and Rehabilitation Medicine. The complete study questionnaire included questions about their sociodemographic backgrounds, lifestyles and health, as well as several well-validated methods. The overall back and leg pain was assessed using a visual analogue scale (VAS) (range: 0–100 mm, with 0 mm indicating ‘no pain’ and 100 mm indicating ‘the worst possible pain’) (Price et al., 1983).

The subjective disability was measured using the validated Finnish version of the Oswestry Disability Index (ODI) (range: 0%–100%, with 0% indicating ‘no disability’ and 100% indicating ‘extreme disability’) (Fairbank et al., 1980; Fairbank and Pynsent, 2000; Grönblad et al., 1993). In addition, SOC scale (Antonovsky, 1981, 1993) was used as a measure of the general coping resources The short, well-validated 13-item version (range: 13–91) of the SOC scale was used (Antonovsky, 1981, 1993; Kivimäki et al., 2000), with responses on a 7-point scale. The following are examples of the items included in the study: ‘In the past, have you been surprised by the behaviour of people whom you thought you knew well?’ (never happened–always happening) and ‘Do you feel that you are being treated unfairly?’ (very often–very seldom or never). A high SOC score reflected stronger coping resources.

The alexithymic features were assessed with a validated Finnish version (Joukamaa et al., 2001) of the 20-item Toronto Alexithymia Scale (TAS-20) (Bagby et al., 1994a, 1994b). The participants indicated how much they agreed with the statements (e.g. ‘I am often confused about what emotions I am feeling’) using a 5-point Likert scale, and the responses ranged from 1 (strongly disagree) to 5 (strongly agree), with a total range of 20–100.

Statistical analyses

All of the statistical analyses were performed using SPSS/PC (version 23.0; SPSS, Chicago, IL, USA), including the χ² with class variables and Student’s t-test with continuous variables. In the group comparisons, the groups were formed according to the mean SOC (mean: 70.2, standard deviation (SD): 12.7) at the baseline: a weak SOC group (scores: 13.0–70.2) and a strong SOC group (scores: 70.3–91.0).

Two separate multivariate binary logistic regression analyses (enter method) were performed to assess the baseline predictors for higher pain at the 10-year follow-up (VAS score over mean: >32.3) and at least moderate disability at the 10-year follow-up (ODI score over 21). The predictors used in both analyses were as follows: sex, age, preoperative VAS score, preoperative ODI score and belonging to the weakest SOC tertile at the baseline (SOC score: 13.0–66.4). The weakest tertile approach for the SOC was used, since there are no established clinical cut-offs for the SOC. Belonging to the routine versus enhanced physiotherapy rehabilitation group was also included as a binary predictor in the preliminary regression analyses, but it gained no statistical significance with respect to the 10-year pain or disability (data not shown).

Results

The mean age of the participants was 61.7 years (SD: 11.2) at the baseline, and out of 99 participants, 42 (42%) were men. At the 10-year follow-up, the mean age was 68.4 years (SD: 9.7), and out of 69 participants, 26 (38%) were men. The mean SOC score was 70.2 (SD: 12.7) at the baseline and 72.0 (SD: 13.3) at the 10-year follow-up; however, the difference between the baseline and 10-year SOC scores was not statistically significant. The mean baseline SOC score of all the dropout participants was 70.5 (SD: 11.1) (including the 17 participants who died during the 10-year follow-up period and the 12 participants who did not fill in the SOC items). Regarding only the surviving dropout participants (n = 12) whose SOC data were not available at the 10-year follow-up, the mean baseline SOC was 65.8 (SD: 14.3). However, there was no significant difference between the mean baseline SOC score of the deceased participants (65.8) and the mean baseline SOC score (70.2) of the all the included participants.

In the cross-sectional analyses, it was found that at the baseline, the participants with a weak SOC had a higher alexithymia score (p < 0.001) than those participants in the strong SOC group. No differences between the groups were seen regarding the age, sex, VAS score for pain or ODI (Table 1).

Table 1.

Baseline characteristics of the LSS patients and their relationships to the baseline weak/strong SOC.

Variable	All (n = 99)	Weak SOC (13–70)	Strong SOC (71–91)	p-value between weak and strong SOC groups
Age: mean (SD)	61.7 (11.2)	61.0 (12.7)	62.0 (10.1)	NS
Sex (% of men)	42	45	55	NS
Visual analogue scale: mean (SD)	55.5 (27.1)	55.7 (27.2)	55.3 (27.3)	NS
Oswestry Disability Score: mean (SD)	44.0 (15.0)	45.0 (15.7)	43.1 (14.6)	NS
Toronto Alexithymia Scale: mean (SD)	46.7 (11.0)	51.6 (10.0)	43.2 (10.4)	***

LSS: lumbar spinal stenosis; SOC: sense of coherence; SD: standard deviation; NS: non-significant. ***p < 0.001.

When comparing the 10-year scores with respect to the baseline weak/strong SOC, it was found that the participants originally in the weak SOC group reported more disability (ODI: p < 0.05) (Table 2).

Table 2.

The 10-year follow-up characteristics of the LSS patients and their relationships to the baseline weak/strong SOC.

Variable	All (n = 69)	Weak SOC (13–70)	Strong SOC (71–91)	p-value between weak and strong SOC groups
Age: mean (SD)	68.4 (9.7)	67.8 (11.5)	69.3 (8.4)	NS
Sex (% of men)	38	54	46	NS
Visual analogue scale: mean (SD)	32.3 (28.4)	39.1 (27.3)	27.9 (28.0)	NS
Oswestry Disability Score: mean (SD)	28.5 (20.9)	36.3 (20.6)	25.6 (20.0)	*
Toronto Alexithymia Scale: mean (SD)	43.8 (11.8)	46.8 (12.1)	41.7 (11.7)	NS

LSS: lumbar spinal stenosis; SOC: sense of coherence; SD: standard deviation; NS: non-significant.

p < 0.05.

In the logistic regression analyses, the preoperative ODI score (p < 0.05) and belonging to the weakest tertile preoperative SOC group (p < 0.05) emerged as independent predictors for 10-year disability (ODI score: >21). When analysing the preoperative predictors for more 10-year pain (VAS score: >32.3), no significant associations were seen, even though the preoperative ODI score almost gained statistical significance (p = 0.05) (Table 3).

Table 3.

Logistic regression models showing the odds ratios (with 95% confidence intervals) of the sociodemographic and preoperative variables predicting 10-year disability and pain.

Predictor	Oswestry ⩾ moderate disability (21): no/yes	Visual analogue > mean (32.3): no/yes
Gender (male: no/yes)	0.44 (0.13–1.43)	0.52 (0.14–1.88)
Age (years: continuous variable)	1.02 (0.95–1.08)	1.04 (0.97–1.11)
Visual analogue scale (mm: continuous variable)	0.99 (0.97–1.02)	1.02 (0.99–1.04)
Oswestry (score: continuous variable)	1.05 (1.00–1.10) *	1.05 (1.00–1.10) (p = 0.05)
Sense of coherence (belonging to weakest scoring tertile; score 13.0–66.4: no/yes)	3.71 (1.02–13.48) *	1.56 (0.44–5.51)

p < 0.05.

Discussion

First, an important and thought-provoking finding of this study was that the preoperative SOC was predictive of the LSS patients’ functional ability 10 years after the surgery. Even though the overall SOC level in our study population was relatively stable and strong (Volanen et al., 2007), both pre- and postoperatively, this association became evident when the focus was set on the weakest scoring tertile in the SOC at the baseline and its predictive value. There have been no previous 10-year follow-up studies regarding the SOC of LSS patients, but in an interesting parallel, a 5-year follow-up study (Santavirta et al., 1996) proved that a strong SOC was protective against functional decline after an anterior lumbar fusion. In our study, the significance of SOC with respect to the LSS surgery outcome was not totally unexpected; although as it has been previously reported, those LSS patients with weaker SOC showed poorer trajectories of postoperative recovery at the 3-month follow-up (Sinikallio et al., 2011b) and the weaker 3-month SOC is also predictive of the 5-year surgery outcome in LSS (Pakarinen et al., 2017). This study, however, points to the importance of the preoperative SOC as well, and we find this noteworthy. Over the long term, it is also the preoperative mixture of optimism and sense of control (i.e. the SOC components: comprehensibility, manageability and meaningfulness) of the patients that is important with respect to their functional ability, even 10 years after the surgery. Interestingly, SOC has been studied both as a risk factor and a resource factor and either way, it seems to resonate in a clinically meaningful manner, although the original conceptualization by Antonovsky defined SOC as a psychological resource factor. The preoperative disability (ODI score) was another factor that was associated with the 10-year disability, an association that seems logical, in that those with more preoperative disability are prone to somewhat more postoperative disability after 10 years.

Second, when taking a look at the cross-sectional analyses, we found that a weaker preoperative SOC was associated with a higher alexithymia score. However, previous studies on the relationship between SOC and alexithymia are scarce, and more studies are needed to elaborate this association. On a more general level, some studies have found an association between alexithymia and lower back pain (Pecukonis, 2009; Von Korn et al., 2014), but in our study, the mean baseline TAS score (47 points) of the participants was well below the cut-off (61 points) used for alexithymia (Bagby et al., 1994a).

In addition, our results showed that those participants with a weaker SOC before surgery showed poorer functional ability 10 years after the surgery, but not preoperatively. Again, a weak SOC seems to associate with poorer long-term outcome, as was the case in the earlier postoperative phase (Sinikallio et al., 2011b). Interestingly, a recent study on very elderly participants (80 years or older) (Boeckxstaens et al., 2016) suggested that SOC is not only associated with perceived health but also with functional ability and even mortality. The etiological pathways linking SOC and disability deserve some attention, since previous research has suggested that a strong SOC buffers health adversity through psychological ‘inner strength’ (including resilience, positive emotionality and adaptation) (Hart et al., 2006; Lundman et al., 2010; Nygren et al., 2005), as well as through better stress-related immune function (Lutgendorf and Costanzo, 2003; Piazza et al., 2010). Therefore, future SOC studies need to incorporate not only psychosocial and behavioural assessments but also biomarkers of health and disease, such as the function of the immune system or the hypothalamic–pituitary–adrenal axis (Piazza et al., 2010).

As a limitation of this study, only the use only self-assessment questionnaires must be mentioned. Incorporating functional and biological/physiological measurements may have indeed given a more versatile picture of the studied associations.

Lack of control group may be mentioned as another limitation of a clinical study such as ours. Nonetheless, although randomized controlled trials (RCTs) are generally regarded as methodologically superior to clinical trials, RCTs in clinical research are ethically controversial because the participants in the control group may be denied an effective treatment. This dilemma applies to our study design as we aimed to study the significance of a psychological factor with respect to long-term outcome after (needed) surgical treatment in a patient group with a particular diagnosis. Therefore, comparison with other back pain patient groups is not plausible.

Our study sample was clinical, and our study design naturalistic, as opposed to a strictly selected and controlled experimental sample with lesser potential confounding factors. However, this also means that our results are applicable to LSS patients treated surgically on a secondary care level. The strengths of our study also include the use of well-validated questionnaires and a long-term follow-up in a prospective setting.

In all, the results of this study show that weak preoperative SOC of LSS patients is associated with preoperative alexithymia, but not with disability or pain. Strikingly, the significance of the preoperative SOC seems to extend even to the 10-year postsurgical phase, in which those with a weak preoperative SOC showed poorer functional ability 10 years after the surgery. In addition, a weak preoperative SOC (weakest tertile score) was predictive of the 10-year disability.

What are the clinical implications of these results? In cases of acute lower back pain, the evidence has shown that targeting (identifying and addressing) ‘yellow flags’ (psychological risk factors), particularly when they are at high levels, does seem to lead to more consistently positive results regarding disability (Nicholas et al., 2011). The patients’ own activity and propensity to engage in positive health has been identified as an important modifier of the recovery process, leading to better outcomes and increased compliance towards physical therapy after lumbar surgery (Skolasky et al., 2008).

In cases of surgically treated LSS, a weak SOC could be a potential yellow flag candidate to be identified and intervened preoperatively. Although there are no previous interventional studies on the SOC of LSS patients, a recent study (Tan et al., 2016) within a community-dwelling elderly population (65 years or older) showed that the SOC can be enhanced with a salutogenic self-care programme leading to better health. Moreover, considering the persistent connection between preoperative disability and 10-year disability in our results, a question arises of whether preoperative rehabilitation could strengthen the postsurgical functional ability of LSS patients. This approach is currently being studied by Marchand et al. (2015) who have designed an RCT study to determine the effects of an active preoperative intervention programme on the clinical parameters and functional physical capacity in patients undergoing LSS surgery. Our results suggest that the preoperative strategies to optimize long-term postoperative recovery might include physical rehabilitation as well as strengthening the salutogenic resources of LSS patients.

Footnotes

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) received no financial support for the research, authorship and/or publication of this article.

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