Boosted protease inhibitor monotherapy as a maintenance strategy: an observational study.
We aimed to determine the effectiveness of boosted protease inhibitor monotherapy (BPIMT) initiated as a maintenance strategy in routine care and identify predictive factors of failure. Observational study in the FHDH-ANRS CO4 cohort. Five hundred and twenty-nine virologically suppressed individuals switched to BPIMT in the period 2006-2010, 75% had at least 12 and 49% at least 24 months of follow-up. Virological failure (two consecutive HIV-RNA > 50 copies/ml or one HIV-RNA > 50 copies/ml followed by BPIMT discontinuation) and treatment failure (virological failure, antiretroviral reintensification or death) were analysed separately. At baseline, 11% were protease inhibitor-naive, median duration on combined antiretroviral therapy was 84 months and median duration of suppressed viremia was 38 months. Nine percent had a history of virological failure, while on a protease inhibitor-containing regimen, and rates of virological failure were higher among those individuals [adjusted hazard ratio, 1.6; 95% confidence interval (CI), 0.9-2.9]. Compared to individuals with less than 1 year of sustained virological suppression before the switch to BPIMT, those with longer duration were less likely to experience virological failure [hazard ratio, 0.7; (95% CI, 0.4-1.2) and 0.6 (95%CI, 0.4-0.9)] for a duration of 12-23 months and 24 months or more, respectively. Rates of failure were similar for BPIMT with lopinavir-ritonavir (RTV) or darunavir-RTV, but increased for BPIMT with atazanavir-RTV. Same risk factors were associated with treatment failure. The safety and efficacy of a maintenance strategy with BPIMT in a routine care setting matched the results of randomized clinical trials. A longer duration since last virological rebound before switching to BPIMT was associated with a decreased risk of subsequent failure.