Review
Interventions to increase antiretroviral adherence in sub-Saharan Africa: a systematic review of evaluation studies

https://doi.org/10.1016/S1473-3099(11)70181-5Get rights and content

Summary

The success of potent antiretroviral treatment for HIV infection is primarily determined by adherence. We systematically review the evidence of effectiveness of interventions to increase adherence to antiretroviral treatment in sub-Saharan Africa. We identified 27 relevant reports from 26 studies of behavioural, cognitive, biological, structural, and combination interventions done between 2003 and 2010. Despite study diversity and limitations, evidence suggests that treatment supporters, directly observed therapy, mobile-phone text messages, diary cards, and food rations can effectively increase adherence in sub-Saharan Africa. However, some interventions are unlikely to have large or lasting effects, and others are effective only in specific settings. These findings emphasise the need for more research, particularly for randomised controlled trials, to examine the effect of context and specific features of intervention content on effectiveness. Future work should assess intervention targeting and selection of interventions based on behavioural theories relevant to sub-Saharan Africa.

Introduction

Antiretroviral treatment (ART) can substantially reduce morbidity and mortality in people with HIV.1, 2, 3, 4, 5, 6 However, the clinical effectiveness of ART depends crucially on adherence.7, 8, 9, 10 Studies done before 2005 showed that the greatest effectiveness could only be achieved if patients took at least 95% of prescribed antiretroviral doses.7, 11, 12 More recent studies suggest that treatment with some potent ART regimens, such as those based on ritonavir-boosted protease inhibitors and non-nucleoside reverse-transcriptase inhibitors, can achieve viral suppression at lower adherence,13, 14, 15 and that the adherence needed to prevent viral rebound decreases with duration of suppression.15 However, only sustained high levels of adherence will ensure that life-extending benefits of ART are maximised and risk of viral resistance is minimised,16 and low adherence is the most common reason why potential treatment benefits are not achieved or sustained.17 Poor adherence also substantially increases the health-care costs associated with treatment of HIV in both developing and developed countries.18, 19 Additionally, high adherence is essential for the reduction of HIV transmission in treatment-as-prevention approaches.20

Many national governments in sub-Saharan Africa, with support from international agencies and donors, are striving to provide ART to all people in need.21 Of the more than 5 million people worldwide who were receiving ART at the end of 2009, almost four-fifths were in sub-Saharan Africa,22 where ART adherence might be low.23 Results of a 2006 meta-analysis24 of ART adherence investigations showed that, on average, 23% of patients in studies from sub-Saharan Africa did not achieve adequate adherence, with the proportion of non-adherent patients ranging from 2% to 70% across the primary studies included in the analysis. These findings suggest a need to improve adherence substantially in many settings in sub-Saharan Africa.25 Moreover, most treatment programmes in sub-Saharan Africa have only been enrolling patients for a few years. Experience from developed countries has shown that adherence falls with time on ART,26, 27, 28 and recent studies suggest similar trends in sub-Saharan Africa.29

Interventions to increase ART adherence in sub-Saharan Africa are clearly needed. Most studies of adherence interventions are from developed countries, and many have been previously reviewed.25, 30, 31, 32, 33, 34, 35, 36, 37, 38 Table 1 provides an overview of categories of interventions to improve ART adherence that have been investigated in the developed world.30, 31, 39 The evidence from these investigations might, however, have limited relevance to sub-Saharan Africa because the effectiveness of interventions is likely to depend on the context in which they are implemented. For example, adherence interventions in developed countries are usually provided by general nurses, pharmacists, or physicians,30, 34 while in sub-Saharan Africa health workers specifically trained to care for patients with HIV are commonly responsible for the monitoring and support of ART patients, often with little involvement from physicians.40 Further, interventions in developed countries might be based on theories of behaviour that are not valid in sub-Saharan Africa, and those that have been specifically tailored to adherence support of specific subpopulations (such as men who have sex with men41 or injection drug users30) might be of little use in the generalised HIV epidemics of sub-Saharan Africa. Resource-intensive interventions directed towards the individual (eg, cognitive behavioural therapy42) could be difficult to implement in sub-Saharan Africa because of large numbers of patients, restricted resources, and the public health approach to treatment.

Therefore, evidence from sub-Saharan Africa is important to inform the design and implementation of ART adherence interventions in the region. We present findings from a systematic review of studies investigating the effectiveness of ART adherence interventions in sub-Saharan Africa.

Section snippets

Search strategy

We systematically searched PubMed for studies that were published before 31 Jan, 2011, and evaluated interventions to improve ART adherence in sub-Saharan Africa. To identify articles for this Review, we combined two broad search themes with the Boolean operator “and”. The first search theme—ART—combined the Medical Subject Headings (MeSH) terms “antiretroviral therapy, highly active” and “anti-HIV agents”, and the free-text word “antiretroviral”, with the Boolean operator “or”. The second

Study selection process

27 reports from 26 studies met all inclusion and exclusion criteria (figure): 17 journal articles,56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72 seven conference abstracts,73, 74, 75, 76, 77, 78, 79 one master's thesis,80 one research report,81 and one research letter.82 Five reports were from Nigeria,57, 66, 73, 75, 76 five from South Africa,71, 77, 78, 80, 81 four from Kenya,61, 67, 70, 79 three from Mozambique,60, 62, 63 three from Uganda,68, 74, 82 two from Malawi,58, 59

Discussion

Several important insights have emerged from this systematic review of interventions to increase ART adherence in sub-Saharan Africa. The reviewed studies investigated six types of adherence-enhancing interventions: text messages and other reminder devices, treatment supporters, directly observed therapy, education and counselling, food supplements, and different health-systems approaches to ART delivery. For each intervention type there is at least one randomised controlled trial60, 61, 66, 67

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