Human immunodeficiency virus 1 protease inhibitors in clinical practice - Predictors of virological outcome

Objectives: To ascertain whether prolonged suppression of viral replication can be achieved in clinical practice and to identify factors associated with virological outcome. Design: Retrospective observational study. Setting: University-affiliated human immunodeficiency virus (HIV) clinic in Cleveland, Ohio. Participants: Patients treated with regimens that included protease inhibitors between June 1995 and December 1997. We identified 366 patients; 310 had sufficient virological follow-up data to be included. Main outcome Measure: Virological success was defined as plasma HIV-RNA levels lower than 400 copies/mL at the last clinic visit. Virological failure was subdivided according to the maximum degree of suppression of viral replication achieved. Multivariate analysis was performed to identify baseline factors associated with virological outcome. Results: Virological success was achieved by 47% of patients at a median follow-up of 335 days. The median CD4(+) cell count increase and HIV-RNA level decrease were 0.10 x 10(9)/L (100 cells/mu L) and greater than 1.3 log(10) in patients who achieved virological success, and 0.010 X 10(9)/L and 0.32 log(10) for those who did not. In multivariate analysis the likelihood of virological success was diminished in women (P < .02) and in patients who missed 2 or more clinic visits in the prior year (P < .001), and decreased when the regimen was started earlier (P < .04). Patients with a lower nadir CD+ cell. count (P < .04) and higher peak plasma HIV-RNA levels (P < .001) also had a decreased likelihood of virological success. Conclusions: More than half the patients who started a regimen that included protease inhibitors in an academic clinical practice failed to achieve durable suppression of viral replication and also experienced a poorer immunologic outcome as determined by CD4(+) cell count increase. Missed clinic visits, more advanced disease, and higher plasma HIV-RNA levels may predict failure.