Background: Adherence to antiretroviral therapy is critical to successful treatment of human immunodeficiency virus (HIV). Few interventions have been demonstrated to improve both adherence and virologic outcomes. We sought to determine whether an intervention derived from problem solving theory, Managed Problem Solving (MAPS), would improve antiretroviral outcomes. Methods: We conducted a randomized investigator blind trial of MAPS compared with usual care in HIV-1 infected individuals at 3 HIV clinics in Philadelphia, Pennsylvania. Eligible patients had plasma HIV-1 viral loads greater than 1000 copies/mL and were initiating or changing therapy. Managed Problem Solving consists of 4 in-person and 12 telephone-based meetings with a trained interventionist, then monthly follow-up calls for a year. Primary outcome was medication adherence measured using electronic monitors, summarized as fraction of doses taken quarterly over 1 year. Secondary outcome was undetectable HIV viral load over 1 year. We assessed 218 for eligibility, with 190 eligible and 180 enrolled, 91 randomized to MAPS and 89 to usual care. Fifty-six participants were lost to follow-up: 33 in the MAPS group and 23 in usual care group. Results: In primary intention-to-treat analyses, the odds of being in a higher adherence category was 1.78 (95% CI, 1.07-2.96) times greater for MAPS than usual care. In secondary analyses, the odds of an undetectable viral load was 1.48 (95% CI, 0.94-2.31) times greater for MAPS than usual care. In as-treated analyses, the effect of MAPS was stronger for both outcomes. There was neither a difference by prior treatment status nor change in effect over time. Conclusions: Managed Problem Solving is an effective antiretroviral adherence intervention over the first year with a new regimen. It was equally effective at improving adherence in treatment experienced and naive patients and did not lose effect over time. Implementation of MAPS should be strongly considered where resources are available. Trial Registration: clinicaltrials.gov Identifier: NCT00130273
