Systematic review: effect of alcohol intake on adherence to outpatient medication regimens for chronic diseases

Nonadherence to medications can lead to adverse health outcomes. Alcohol consumption has been shown to be associated with nonadherence to antiretroviral medications, but this relationship has not been examined at different drinking levels or with other chronic disease medications. We conducted a narrative synthesis of the association of alcohol consumption with nonadherence to medications for four chronic diseases.

We searched MEDLINE, PsycINFO, Cochrane Library, and Web of Science for relevant studies published through 2009. To be included in this analysis, studies had to be quantitative; have a sample size of 50 or greater; and examine the effect of alcohol consumption on medication adherence for diabetes, hypertension, depression, or HIV/AIDS. Study characteristics and results were abstracted according to pre-specified criteria, and study quality was assessed. Study heterogeneity prevented a systematic synthesis.

Sixty eligible studies addressed medication adherence for HIV in 47 (78%), diabetes in 6 (10%), hypertension in 2 (3%), both diabetes and hypertension in 1 (2%), depression in 2 (3%), and all medications in 2 (3%). Mean number of subjects was 245 (range: 57-61,511). Effect sizes for the association of alcohol use with nonadherence varied (0.76-4.76). Six of the seven highest quality studies reported significant effect sizes (p < .05), ranging from 1.43 to 3.6. Most (67%) studies reporting multivariate analyses, but only half of non-HIV medicine studies, reported significant associations.

Most studies reported negative effects of alcohol consumption on adherence, but evidence among non-HIV studies was less consistent. These data suggest the relevance of addressing alcohol use in improving antiretroviral adherence and a need for further rigorous study in non-HIV chronic diseases.