1059 — Adherence to HIV Antiretroviral Drugs is Worse for Protease Inhibitor-Based Regimens than for Non-Nucleoside Reverse Transcriptase Inhibitor-Based Regimens in Veterans
Nelson RE (VA Salt Lake City), Nebeker J
(VA Salt Lake City), Hayden C
(VA Salt Lake City), Reimer L
(VA Salt Lake City), Kone K
(VA Salt Lake City), LaFleur J
(VA Salt Lake City)
Highly active antiretroviral therapy (HAART), composed of 3-4 agents from at least 2 different drug classes, is considered the most effective form of Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) treatment. In order to minimize the risks of treatment failure and the development of resistance, near perfect adherence (>= 95%) is required. Due to more severe side effects, patients may be less adherent to protease inhibitor-based regimens compared to non-nucleoside reverse transcriptase inhibitor (nNRTI)-based regimens. We compared adherence levels over 1 year in patients who initiated a protease inhibitor (PI)-based versus nNRTI-based regimen.
Incident cases of HIV-seropositive, antiretroviral-naïve patients (no prior antiretroviral therapy within the VHA system) initiating therapy from 1998-2006 were identified using data from the Veterans Health Administration (VHA) Clinical Case Registry (CCR). Adherence ratios in the first year were calculated as the proportion of days covered (PDC) with ART medications from 3 or more classes. Patients who discontinued before 1 year were included. Separate multivariable logistic regressions were run with an indicator for PDC>95%, 90%, 85%, and 80%. The key independent variable was an indicator for a regimen that included a PI. We adjusted for age, race, sex, marital status, year therapy was initiated, and Charlson Comorbidity Index.
A total of 929 veterans on PI-based and 747 on nNRTI-based regimens were included in the study. The mean age was 57.2 (SD 8.9) for PI users and 55.4 (SD 9.3) for nNRTI user. Only 19.7% of patients on a PI had PDC > 80% while 35.1% of the patients on an nNRTI had adherence above this level. In the multivariable analysis, starting on a regimen that included a PI was associated with poor adherence for each of the 4 adherence thresholds. This effect was significant for the 90% (OR=0.692, 95% CI 0.495-0.969), 85% (OR=0.739, 95% CI 0.547-0.998), and 80% (OR=0.701, 95% CI 0.532-0.924) adherence thresholds.
Patients initiating HAART with a regimen that included a PI had worse adherence than those who started on an nNRTI.
Knowledge of which regimens are associated with better adherence will help clinicians choose an ART regimen that will optimize adherence.