Strategies to improve adherence to medications for cardiovascular diseases in socioeconomically disadvantaged populations: a systematic review

Medication non-adherence poses a major barrier to reducing cardiovascular disease (CVD) burden globally, and is increasingly recognised as a socioeconomically determined problem. Strategies promoting CVD medication adherence appear of moderate effectiveness and cost-effectiveness. Potentially, 'one-size-fits-all' measures are ill-equipped to address heterogeneous adherence behaviour between social groups. This review aims to determine the effects of strategies to improve adherence to CVD-related medications in socioeconomically disadvantaged groups. Randomised/quasi-randomised controlled trials (1996-June 2012, English), testing strategies to increase adherence to CVD-related medications prescribed to adult patients who may experience health inequity (place of residence, occupation, education, or socioeconomic position) were reviewed. 772 abstracts were screened, 111 full-text articles retrieved, and 16 full-text articles reporting on 14 studies, involving 7739 patients (age range 41-66 years), were included. Methodological and clinical heterogeneity precluded quantitative data synthesis. Studies were thematically grouped by targeted outcomes; underlying interventions and policies were classified using Michie et al.'s Behaviour Change Wheel. Contrasting with patient or physician/practice strategies, those simultaneously directed at patients and physicians/practices resulted in statistically significant improvements in relative adherence (16-169%). Comparative cost and cost-effectiveness analyses from three studies did not find cost-saving or cost-effective strategies. Unlike much current evidence in general populations, promising evidence exists about what strategies improve adherence in disadvantaged groups. These strategies were generally complex: simultaneously targeting patients and physicians; addressing social, financial, and treatment-related adherence barriers; and supported by broader guidelines, regulatory and communication-based policies. Given their complexity and potential resource implications, comprehensive process evaluations and cost and cost-effectiveness evidence are urgently needed.