Predictors of short-term success of antiretroviral therapy in HIV infection.

Objectives: The success of highly active antiretroviral therapy (HAART) in HIV infection may be influenced by numerous host factors. There is a lack of data presenting a combined assessment of a variety of these parameters for treatment efficacy in clinical routine practice.

Methods: Different indices of therapeutic drug monitoring (TDM) were evaluated prospectively in the context of self-reported adherence, health-related quality of life and social determinants, as measured by a questionnaire.

Results: A total of 210 individuals were studied between 2002 and 2004, 77% were males, mean age was 44 years, mean CD4 count was 336 cells/mm3 and 63% had a viral load < 50 copies/mL. In univariate analysis, baseline viral load, unscheduled drug levels, a 4 h pharmacokinetic profile (PK-P) at a scheduled visit and self-reported complete adherence within the previous 2 weeks were significantly associated with virological success of HAART at 12 weeks. At 24 weeks, only baseline viral load, the 4 h PK-P and adherence were significantly associated with HAART efficacy. In multivariate analysis, baseline viral load, adherence, unscheduled drug levels, trough levels at a visit with appointment as well as the 4 h PK-P were significantly associated with virological success at 12 weeks. At 24 weeks, only adherence was significantly linked to outcome. The other parameters were not found to have an impact on treatment efficacy.

Conclusions: TDM and self-reported adherence were independently predictive of short-term HAART success in this prospective study. Unscheduled drug measurements provided similar diagnostic information as a 4 h PK-P. Thus, we propose the use of unscheduled drug level monitoring and self-reported adherence to help identify patients with elevated risk of virological failure.