Factors predicting response to antiretroviral regimens with a protease inhibitor in HIV-infected subjects

OBJECTIVE: To investigate factors related to early virological response amo ng a cohort: of 224 patients who started a protease inhibitor (PI) for the first time. To determine which factors are associated with persistent respo nse among patients with early response. PATIENTS AND METHODS: Early complete response was defined as an undetectabl e plasma viral load 2 to 3 months after treatment onset (< 400 copies/ml, Q uantiplex HIV 2.0 Chiron diagnostics), incomplete response as at least 1 lo g reduction of viral load. in patients with an undetectable plasma Viral lo ad at 2 or 3 months, we also assessed the persistence of the response on th e same regimen. Virology failure was defined by two consecutive viral load levels above the detection limit. RESULTS: In the total cohort, 66% of the patients had an early complete res ponse, 11% a partial response and 23% no response. Complete virological res ponse was significantly more frequent in naive (89%) than in pretreated (59 %) patients (p< 0.001). Multivariate analysis of factors predictive of earl y response in pretreated patients (n = 169) showed that viral load (p = 0.0 01), the number of nucleoside analogs previously received (p = 0.06) and a full or partial treatment switch (p = 0.10) were associated with complete r esponse. Analysis of later response in the 45 naive patients with prolonged follow-up showed that 22% had treatment failure after 3 to 16 months. None of the baseline variables (viral load, CD4+ cell count or nature of the PI ) were associated with duration of response. The only factor associated wit h persistent response in pretreated patients was a low number of antiretrov iral drugs previously received (log-rank test, p = 0.04). CONCLUSIONS: The absence of previous antiretroviral treatment as the main f actor associated with an early complete virological response. in patients p retreated with nucleoside analogs who presented early virological success, the number of drugs previously received, often associated with full or part ial switch of nucleoside analog, significantly influence the persistence of response to a given triple-drug regimen.