Efficacy of antiretroviral therapy adherence interventions: a research synthesis of trials, 1996 to 2004

OBJECTIVE: To conduct a quantitative review of published trials of antiretroviral therapy (ART) adherence interventions. DESIGN: A research synthesis of published ART adherence intervention outcome studies. SAMPLE: ART adherence intervention outcome studies meeting inclusion criteria published between 1996 and December 2004 (k=24). MAIN OUTCOME MEASURE: Effect sizes (ESs [d]) were calculated for each study outcome, producing 25 immediate postintervention outcomes and an additional 13 follow-up ESs. Reported pre- to post-ART adherence between groups (k = 15) or within groups (k = 10) served as the main outcome converted to standardized ES. RESULTS: ART adherence interventions had a small effect (d = 0.35, odds ratio [OR] = 1.88) that varied considerably across studies. Interventions that specifically enrolled participants with known or anticipated problems with ART adherence demonstrated medium effects on adherence (d = 0.62, OR = 3.07). Interventions that did not target their participants on similar criteria had quite small effects(d = 0.19, OR = 1.41). Adherence improvements showed no tendency to decay across time. CONCLUSIONS: Outcomes of studies targeting those with poor ART adherence had stronger effects than those intervening with groups of individuals who were mixed in terms of pretest levels of adherence. Adherence intervention outcome studies must carefully delineate their target populations, because defining individuals as "on ART" does not provide the level of specificity needed to design and implement effective interventions.