Influence of Prior Antiretroviral Experience on Adherence and Responses to New Highly Active Antiretroviral Therapy Regimens

Abstract

The impact of prior antiretroviral experience on adherence and clinical outcomes in patients initiating a new highly active antiretroviral therapy (HAART) regimen is not well defined. We performed an observational cohort analysis of antiretroviral-experienced or -naive HIV-infected patients prescribed a new HAART regimen (3538 patients) and enrolled in Kaiser Permanente Northern California from 1997 through 2002. Outcomes evaluated were HAART adherence and changes in HIV RNA level and CD4 T-cell counts over 12 and 24 months. The antiretroviral-naive group had a significantly greater odds of achieving >/=95% adherence to the HAART regimen over 12 months (adjusted odds ratio [OR] = 1.88, p < 0.001) and over 24 months (OR = 1.66, p < 0.001). The odds of achieving HIV RNA levels below limits of quantification also was higher among patients who were antiretroviral naive; over 24 months OR = 6.88, p < 0.001. Adjusted change in CD4 T-cell count was also greater among naive patients over 24 months (+67 cells/muL, p < 0.001), compared to antiretroviral-experienced patients. Years of antiretroviral experience did not affect adherence or any outcome measure. Adjusting for HAART adherence did not significantly affect HIV RNA results but did lessen CD4 T-cell count differences between antiretroviral-naive and -experienced patients. Thus, antiretroviral naive patients have improved HAART adherence, HIV RNA control, and CD4 T-cell count increases compared to antiretroviral-experienced patients regardless of years of antiretroviral experience. These findings should help direct HAART adherence efforts in HIV care clinics.