Factors affecting antiretroviral therapy adherence among HIV-positive pregnant and postpartum women: an adapted systematic review

Abstract

Summary

Adherence to antiretroviral therapy (ART) is crucial for effective treatment, but can be quite complex. Non-adherence can adversely affect treatment outcomes. Although many studies have been done on adherence in the general population, few have included HIV-positive pregnant and postpartum women in resource-constrained settings. This review assessed the evidence on adherence among these groups of women. A systematic search of databases was completed between June and July 2011. Both qualitative and quantitative studies were included. Eighteen studies from a total of 6622 satisfied the inclusion criteria that included inter alia facilitators and barriers to adherence. This review highlighted that there is still no consensus on the definition and measurement of adherence; also multiple factors can affect a woman's ability to adhere to ART. Some of the barriers and facilitators identified were similar in both the type of study (qualitative and quantitative) and among the various countries. Findings indicated that the few studies in this population are conducted primarily in resource-rich settings. Such paucity of information warrants urgent attention; thus targeted research is needed to provide insight on adherence within this population.

Keywords

Adherence antiretroviral therapy ART HIV AIDS women pregnant postpartum

Adherence to treatment and care regimens has historically been problematic due to the increasing prevalence of chronic diseases and their reliance on individuals’ self-care.¹ The literature defines adherence as the level to which patients follow medical advice or treatment plans such as taking medications, keeping medical appointments and maintaining lifestyle changes.^1,2

Adherence to treatment for chronic diseases such as asthma, hypertension and diabetes is about 50% among persons who are aware of the nature of their illness to 30% among those who do not.³ In a review of published studies on adherence over a 50-year period, DiMatteo¹ obtained a range of adherence from a mean of 65.5% for sleep disorders to 88.3% for HIV.

Although highly active antiretroviral therapy (HAART) to treat HIV has significantly reduced AIDS-related morbidity and mortality, success with HAART is closely associated with consistent and correct use of medication. Maintaining compliance with medication of 95% or greater has been associated with adequate viral suppression.^{4

–7}

Thirty years into the HIV/AIDS epidemic, women are now disproportionately affected and a growing casualty of this disease. Women of reproductive age are at risk of transmitting the virus to their offspring via mother-to-child transmission (MTCT). But transmission can be reduced to less than 2%^8,9 with the use of HAART together with safer delivery and infant feeding options.

Adherence to HAART is thus an important concern in this population, since non-adherence can lead to an upsurge of virus in the body, disease progression, increased risk of MTCT and resistant strains, which can be transmitted to the general population. These resistant strains are more difficult and expensive to treat, creating significant public health challenges.^10,11

Adherence to HAART can be complicated since a variety of factors can adversely affect treatment outcome. These factors can be grouped into three categories: namely treatment – ART regimen and its adverse effects,^3,7 patient – socioeconomic and psychosocial factors^7,12 and the health-care system – access to health-care and support from health-care staff.^7,12

Horne et al. ¹³ and Horne and Weinman¹⁴ explored another important patient factor which impacts on adherence: namely, a person's ‘beliefs’ about the need for medication and ‘concerns’ about negative side-effects. Based on these two concepts, the patient will make a determination on whether to take their medication, dosing frequency and the length of time for treatment.¹⁵ In another study by Horne et al.,¹⁶ the researchers identified the influential role of culture and ethnicity on health behaviour; particularly, a patient's use and adherence to Western (allopathic) medicine, whereby the patient believes that these medications are prescribed unnecessarily, are unsafe, and thus detrimental to health.

This multiplicity of factors described above can adversely affect adherence highlighting the importance of accessing patient readiness for ART as advocated by WHO antiretroviral therapy guidelines.¹⁷ Balfour et al. ¹⁸ noted the paucity of adherence interventions and emphasized the need to have interventions prior to HAART initiation to offset misinformation, fears, stress and depression and developed a theoretically based tool to determine ART readiness. Nordqvist et al. ¹⁹ and Fowler²⁰ also emphasized the importance of determining readiness to access care and treatment services with the use of simple tools for assessment and the need to customize interventions for the individual. However, behaviour change takes time, and therein lies the challenge for pregnant women, since timing is important for their treatment to be effective. Women who would have been diagnosed in the current pregnancy have to grapple with issues surrounding their newly diagnosed status and the impending pregnancy, while those already on treatment struggle with similar pregnancy-related issues and changes in ARV regimen, all of which can hamper adherence.

HAART adherence can be measured by a variety of methods such as patient self-reports,^{21

–24} provider reports,^21,23,24 pill counting and pharmacy reports,^{22
–24} electronic devices, such as the Medication Event Monitoring System (MEMS),^5,25,26 biochemical reports^6,22,26,27 and surrogate markers.²⁸

Unfortunately, there is no ideal or ‘gold standard’²⁹ measurement for adherence since some of the methods listed above have either underestimated or overestimated adherence behaviour. Therefore, multiple approaches are needed to assess adherence in order to tailor the regimen to individual circumstances.

Researchers have also noted different patterns of adherence among non-adherers, including changes in the same individual over time and called for an understanding of these patterns and ‘simple’ measures of measurement in order to develop targeted interventions.^26,30,31

There is a paucity of research on adherence and its determinants among seropositive pregnant and postpartum women in international settings, particularly in developing countries. Therefore, the proposed research intends to conduct a systematic review of the literature to determine the studies that address the risk factors and determinants of adherence in this population.

METHODS

Search strategy

A systematic literature search was conducted for both qualitative and quantitative studies in both resource-rich and resource-constrained countries, with a focus on the latter settings to determine among other things what research had been done in the field of adherence as it pertains to pregnant and postpartum women. There were no date limits on the searches, but studies were limited to those written in English which included the study population.

The review was limited to studies identified from the University College London (UCL) Library between June and July 2011. Electronic databases included OVID MEDLINE (1948 to present), OVID EMBASE (1980 to present), OVID PsycINFO (1806 to present), EBSCO CINAHL Plus (1984 to present), JSTOR (1995 to present), ISI Web of Science (1900 to present) and The Cochrane Library (1996 to present). Key individual journals such as AIDS Care (7 July 2011), AIDS Patient Care and STDs (6 July 2011), International Journal of STDs and AIDS (6 July 2011), AIDS and Behavior (5 July 2011), Women and Health (5 July 2011) and Social Science and Medicine (5 July 2011) were also searched electronically. In addition, the reference section for selected studies from the electronic and hand searches above were screened for other relevant studies. Search terms included ‘HIV’, ‘AIDS’, ‘mother-to-child transmission’, ‘MTCT’, ‘PMTCT’, ‘ARV therapy’, ‘HAART’ and ‘medication adherence’.

Eligibility criteria for the review

The PICOS (participants, interventions, comparators, outcomes and study design) methodology as advocated by the PRISMA Statement³² was integrated into this systematic review process. Types of studies: all types of designs (qualitative and quantitative) were considered since this was a scoping exercise to determine among other things what research has been conducted in the field of adherence as it pertains to pregnant and postpartum women; types of participants: participants were HIV-positive pregnant and postpartum women receiving ART. Studies incorporating men and women or men only were excluded in keeping with the overall aim of the review; types of interventions: ART adherence and adherence to other health behaviour for reducing HIV transmission from mother to infant; types of outcome measures: primary outcomes were facilitators and barriers of adherence, measures of adherence, participants’ views, provider views, levels of adherence and infant's HIV status, and secondary outcomes were quality of life, adverse events of non-adherence, morbidity and mortality.

Study selection

The titles and abstracts identified from the PICOS search criteria were reviewed. If the abstract was not available, the full text was sought, and if unavailable, the study was excluded. The final step was to critically examine the full text of the remaining abstracts to determine final eligibility based on the inclusion criteria. Records, such as letters to the editor and commentaries were excluded from further review.

Data extraction

Data were extracted using a modified data collection form designed using items from Table 7.3.a of the Cochrane Handbook Version 5.1.0.³³ Key information (author, year, participants, methods, interventions, outcomes and results) from each study was summarized on this form.

This review resulted in both qualitative and quantitative studies and the author utilized the Clinical Appraisal Skills Program (CASP) tool for qualitative studies (Solutions for Public Health [SPH] an NHS organization, Oxfordshire, UK) and the Effective Public Health Practice Project (EPHPP) for quantitative studies from McMaster University, Ontario, Canada recommended by the Cochrane Health Promotion and Public Health Field Guidelines.³⁴

The EPHPP for quantitative studies has rating scales of Strong = 1; Moderate = 2 and Weak = 3 for measuring selection bias (external validity), study design, confounders, blinding (detection bias), data collection methods, and withdrawals and dropouts (attrition bias). After these individual ratings per component, a final overall rating is issued as follows. If the study has no ‘weak’ grades, it is considered ‘Strong’; one ‘weak’ grade, it is ‘Moderate’; and at least two ‘weak’ grades, it is ‘Weak’.

The qualitative studies were assessed using the Critical Appraisal Skills Program (CASP), a 10-item tool for qualitative research. Information for each study was noted on the extraction form. The criteria for this tool are Aims, Methods, Research design, Sampling, Data collection, Reflexivity, Ethics, Data analysis, Findings and Value. Although this qualitative tool did not have grading criteria, an overall assessment was made of the study as being good, fair or poor, based on the number of ‘yes’ responses.

RESULTS

Searches of the electronic bibliographic databases yielded 881 studies, while hand searches of journals resulted in 5756 studies. Finally, ancestry searches (checking the references of included studies) retrieved 57 for a grand total of 6694 research studies. Seventy-two duplicate studies were eliminated for a balance of 6622 studies. After screening by title and abstract, 37 full-text studies were subjected to complete review, resulting in a final selection of 18 included studies as depicted in the adapted PRISMA flow diagram in Figure 1.³²
Figure 1.
Study selection flow diagram.

Characteristics of excluded studies

Although the 19 excluded studies dealt with adherence to HAART, the study population did not include HIV-positive pregnant and/or postpartum women. The studies were conducted in USA (11), UK (1), Africa (3) and (4) were non-specific to the location.

Characteristics of included studies

The 18 studies which satisfied the eligibility criteria for inclusion were conducted in USA (8), Africa (7), Australia (1), Brazil (1) and Puerto Rico (1). None of the studies were randomized controlled trials (RCTs). Instead, they were as listed below:

Participants

Participants ranged in age from 12 to 58 years. Seven of the studies were conducted in Africa, while the eight studies in the USA were primarily among African Americans, Hispanics and Whites. Participants were HIV-positive pregnant or postpartum women or HIV-positive women with young children. Studies were conducted at clinics and/or hospitals managed by governments or universities.

Interventions

Adherence to ARVs was measured by self reports, pill counts, MEMS caps, blood and urine assays and pharmacy or Medicaid claims. Some studies used in-depth interviews and focus group discussions to highlight the personal perspectives or experiences of the women. Other key variables considered were sociodemographics, drug/alcohol use, mental health/depression, social support and disclosure.

Outcomes

The primary outcome of adherence was assessed with different criteria and measurements in the various studies. Measures of adherence included good adherence ≥95%,³⁵ recent and extended adherence,³⁶ complete adherence = taking all ART doses over the past four days.³⁷ Adherence ranged from a mean of 50%³⁸ to 61% of the women³⁹ during the prenatal period, but declined during the postpartum period.

Quantitative studies

None of the studies received a ‘strong’ rating as per the EPHPP guidelines; four were considered ‘moderate’^{36,40
–42} and the remaining eleven were ‘weak’.^{35,37
–39,43

–49}

Measuring adherence

A variety of techniques were used to measure adherence, primarily pill counts, biological assays and self reports. The definitions and measurements of adherence varied among the studies; definitions included not missing any doses for over three months, taking all medications in the past four days, taking 95% or greater of ART doses for two periods. Some of the measurements taken were as follows: six-month period, second and third trimesters to delivery and past two days.

Levels of adherence

Adherence by the women varied across studies. In the prenatal period it was as low as 50%³⁸ with significant decline (34.1%; 64%) in the postpartum period.^38,49

Factors impacting adherence

Major barriers to adherence included depression,^39,43 non-disclosure of HIV status,^44,50,51 substance use and not taking prescribed prenatal vitamins,³⁶ safety issues/concern for fetus's health,^39,40,52 young age of mother.^41,45,46 Lack of finances, stigma, fear of violence and lack of self efficacy were other contributors to non-adherence.

Major facilitators of adherence were social support from family/friends/partners,^42,51 concern for the fetus/pregnancy,^39,47,51 disclosure to family/friends^41,42 and simplified pill regimen.⁴⁷ Other variables such as older age of the mother, religion, not using drugs/alcohol and not missing prenatal vitamins were more likely to contribute to good adherence. Demographic variables such as ethnicity, marital status⁴² were not associated with adherence.

Qualitative studies

Three qualitative studies^{50
–52} satisfied the inclusion criteria, and received a ‘good’ rating. All had comprehensive aims and appropriate design. Factors affecting adherence both negative and positive were visible during and after pregnancy. Some of the facilitators identified included (1) concern for health of the newborn/infant^51,52 and (2) support from family and friends.⁵¹

Barriers highlighted were (1) issues around daily living;⁵¹ (2) non-disclosure of HIV status;^50,51 (3) financial constraints inclusive of high cost of transportation, poverty, dependence on partner;⁵⁰ (4) stigma;^50,52 (5) health system issues, such as long waiting periods for care;⁵⁰ (6) concerns about safety of the ART;⁵² and (7) being responsible for taking care of others such as other children and family.⁵¹

These three qualitative studies provided an opportunity to understand the experiences of the women from a personalized perspective. Women were concerned about the teratogenic effects of the medication on their offspring⁵¹ and their poor adherence at times stemmed from the women's innate need to protect their children from harm. This was also fuelled by sparse or no information being provided to women about the drugs.

Some women felt that providers only saw them as a disease to be cured and not a person with a disease.⁵² Their views and input into the treatment process were not taken into consideration, resulting in a poor sense of self which adversely affected adherence.

Concern for one's children served as a facilitator for some women and a barrier for others.^51,52 Women who thought that the drugs would be toxic to the fetus and infant were poor adherers, while those who thought that there would be a reduction in transmission to their offspring, and women who wanted to remain in good health to care for themselves and their children were better adherers. Non-disclosure of HIV status to family and friends^50,51 served as a barrier, since women were unwilling to take medication in their presence.

DISCUSSION

The objective of this systematic review was to determine what studies had been conducted on the facilitators and barriers of ART adherence among HIV-positive pregnant women in both resource-rich and resource-constrained countries, and to the author's knowledge is the first such review of this nature.

Few studies were found which satisfied the primary inclusion criterion – pregnant and postpartum women. Eight and seven studies were conducted in the USA and Africa, respectively, while Brazil, Australia and Puerto Rico accounted for one study each. Moreover, studies were predominantly executed in developed countries, as opposed to developing or resource-poor countries such as South East Asia and Caribbean regions.

Such limited information on a key constituent in the HIV/AIDS fight is cause for concern. Non-adherence among this group not only has adverse effects on their own health and future treatment options, but also on the future of the health and wellbeing of their children who might be infected or affected as a result of the mother's poor/non-adherence.

This review process highlights the fact that in addition to the few studies on pregnant and postpartum women, adherence is a complex issue and that there is still no consensus on its measurement and definition. Both the observational and qualitative studies identified myriad factors from the individual to the environment that affects a woman's ability to adhere to her medications. Some of these factors were similar in both the type of study (qualitative and quantitative) and among the various countries.

Definitions and measurements of adherence varied among the studies, which restricted analysis of this key component. Some studies measured adherence via pill counts, MEMS caps, self-reports, while the time span for measurement ranged from days to months. Adherence among pregnant and postpartum women should not be defined as being either 100% adherent or not, since there can be various levels of adherence such as missing doses for short/protracted periods, and not taking certain medications as outlined in the study by Hill et al.³⁰ Adherence is definitely a multifaceted issue and individual characteristics and circumstances need to be taken into account when dealing with this population. There were no studies identified addressing the impact of non-adherence on the mother's health and the infant's HIV or other health status.

Although interventions to improve adherence in pregnant and postpartum women are non-existent at this time, strategies undertaken in the general HIV/AIDS population can be modified for use in this population. Nachega et al. ⁵³ found that support from a ‘treatment buddy’ enhanced adherence; while Goujard et al. ⁵⁴ showed that patient education had an impact on 56% of the experimental group; and a randomized trial in Kenya⁵⁵ found the modified directly-observed therapy, which has been successful in tuberculosis programmes, can be applied with good outcomes among ART patients. An RCT on the use of short text messages (SMS) to improve adherence among 431 adults on ART in rural Kenya by Pop-Eleches et al.⁵⁶ resulted in 53% of respondents with at least 90% adherence as opposed to 40% of respondents in the control group during the 48-week study. Another recently published four-month RCT by daCosta et al. ⁵⁷ among 21 HIV-infected Brazilian women using SMS also indicated increased adherence among the experimental group, albeit with a small sample size.

Some of the strengths of this systematic review include selection of a wide-ranging number of databases, individual journals and ancestry searches. Despite that, few studies were found matching the inclusion criteria resulting in a total of 18 studies. The paucity of information on adherence among pregnant and postpartum women, particularly in resource-constrained countries, warrants urgent attention. As major funding sources such as the Global Fund, World Bank and USAID scale back on financial resources for this epidemic, targeted research is needed on the facilitators and barriers to adherence among this group, that not only measures adherence, but also research that can provide insight on the myriad reasons why women fail to adhere.

It is only by knowing the underlying reasons for this problem can we provide meaningful solutions that go beyond just mere pill counting; research that can provide us with the framework for making changes at the individual level, reduce treatment costs and ensure better health outcomes for women and children.

Footnotes

ACKNOWLEDGEMENTS

This manuscript is part of a wider study for a doctoral thesis. I would like to thank the anonymous reviewers and my supervisors (Professor L. Sherr, Dr Z. Hill and Dr A. Copas) for their insightful comments.

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