An evidence-based review of treatment-related determinants of patients' nonadherence to HIV medications.

Patients' adherence to antiretroviral medications is a primary determinant of both the effectiveness of treatment and the clinical course of HIV/AIDS. This empirical review is intended to compare the relative importance of patient and treatment characteristics on nonadherence behavior and the impact of nonadherence on treatment failure. Articles cited in PubMed and published between 2006 and June 2008 (n = 200) were reviewed to select those that address patient or treatment characteristics associated with nonadherence. Twenty-two articles were selected that provided odds ratio or hazard ratio statistics that quantified predictors of patients' level of nonadherence (e.g., <80%, 80%-95% and >95%). Results were summarized using random effects meta-analytic models. Predictors of nonadherence were divided into four predictive clusters (clinical predictors, comorbid predictors, treatment competence predictors, and dosing predictors). The summary odds ratios (ORs) of nonadherence for each cluster (in order of strength) were treatment competence 2.0 (95% confidence interval [CI]: 1.6-2.6), clinical predictors 1.6 (95% CI: 1.4-1.8), comorbid predictors 1.6 (95% CI: 1.4-1.8), and dosing predictors 1.5 (95% CI: 1.3-1.7). The effect of nonadherence on treatment failure supported the findings of two prior empirical reviews (OR 2.0, 95% CI: 1.6-2.5). Within dosing predictors, a pill burden of more versus less than 10 pills per day was associated with a much higher odds of nonadherence than twice versus once daily dosing or small differences in the number of types of antiretroviral treatments in a regimen. These results provide insight into the relative importance of various determinants of patient nonadherence that may inform the design of patient educational initiatives and initiatives to simplify treatment regimens.