Objectives: To analyze virological and clinical efficacy of protease inhibitor based antiretroviral regimens in a cohort of unselected HIV-infected patients.
Methods: Prospective analysis of all HIV-infected patients started on protease inhibitor therapy until August 31, 1997 in two outpatient clinics. Partial viral suppression was defined as reduction of HIV-RNA at least 1log(10) below baseline and complete viral suppression as reduction below the limit of detection. Risk factors for clinical and virological failure were analyzed by a Cox proportional hazard model.
Results: 387 patients (median observation time 381 days) were analyzed. In 312 patients (81%) partial and in 265 (68%) complete viral suppression was observed. Secondary failure occurred in 75 patients and could be reversed in 11/75. The probability of virological failure at one year was 51% for complete and 47% for partial suppression. CD4-cells increased by a median of 101/microl overall and 39/microl for patients without partial virologic suppression. 57 clinical events or deaths occurred in 44 pts. Risk factors for virological failure were AIDS at baseline (RR 1.6) and use of Saquinavir vs. Indinavir or Ritonavir (RR 1.7), for clinical failure AIDS at baseline (RR 4. 9), CD4-cell count (0.74 for increase of 50/microl), degree of viral suppression (RR 0.1 for complete suppression) and PI used (Saquinavir vs. Indinavir or Ritonavir, RR 2.7).
Conclusions: Virological failure of PI based combination therapy is common and associated with advanced HIV-infection. Clinical failure is associated with advanced HIV-infection and failure to suppress viral replication.