Adherence to highly active antiretroviral therapy in Spain. A meta-analysis.

OBJECTIVES To estimate the percentage of adherence to highly-active antiretroviral therapy (HAART) in Spanish observational studies and to identify the variables associated with adherence. METHODS Seven electronic databases were used to locate the studies. Six inclusion criteria were established. Two coders codified the variables independently. Intercoder reliability was calculated. Publication bias was analyzed through the Begg, Egger and Trim and Fill tests. Homogeneity was evaluated using the Q test and the l² index. A random effects model was assumed to estimate both the overall percentage of adherence and to explain heterogeneity. RESULTS This meta-analysis included 23 observational studies, yielding a total of 34 adherence estimates. The sample was composed of 9,931 HIV-positive individuals (72% men) older than 18 years under treatment with HAART. The percentage of patients adhering to an intake of >90% of the prescribed antiretroviral drugs was 55%. Wide heterogeneity was detected (I² =91.20; 95%CI: 88.75-93.13). Adherence was mainly measured using a single strategy (47.8%), the most widely used being self-report (48.7%). In the univariate analysis, the following factors were significant: infection stages A (β=0.68, p <0.001) and B (β=-0.56, p <0.01), viral loads >200 copies/ml (β=-0.41, p <0.05) and <200 (β=0.39, p <0.05), and university education (β=-0.66, p<0.05). CONCLUSIONS The overall percentage of adherence was 55%, although this value may be an overestimate. Adherence was associated with infection stage A and with a viral load of <200 copies/ml.