The Medication Possession Ratio as a Predictor of Longitudinal HIV-1 Viral Suppression

Antiretroviral adherence is essential to achieve viral suppression and limit HIV-related morbidity and mortality; however, antiretroviral adherence thresholds to achieve viral suppression in clinical practice have not been fully characterized using administrative claims data.

The purpose of this study was to assess the relationship between medication adherence and viral suppression among adult persons with HIV/AIDS (PWH) receiving antiretroviral therapy (ART) for ≥6 months.

This historical cohort, real-world investigation assessed maintenance of viral load suppression and viral load area-under-the-curve (vAUC) in PWH ≥18 years of age based on ART adherence. A marginal effects model was used to determine the predicted probabilities of final plasma HIV-1 RNA <50 copies/mL or vAUC <1,000 copy-days/mL according to the medication possession ratio (MPR), estimated using a Jackknife model variance estimator and a delta-method for marginal effects standard error. Tests for statistical significance used a Šidák method to correct for multiple comparisons.

The mean MPR for ART was 86.7% (95% CI: 85.0%-88.4%) for the 372 PWH included in the study. The marginal effects analysis indicated that an MPR ≥82% was associated with a predicted probability of viral suppression <50 copies/mL (P < 0.05). Significant predicted probabilities for vAUC <1,000 copy-days/mL were observed with an MPR ≥90% (P < 0.05).

Medication possession ratio as a proxy for drug exposure was significantly and consistently associated with viral suppression using a longitudinal measure of HIV viremia. These findings can aid clinicians in the clinical management of PWH and inform future studies of adherence-viral suppression relationships with contemporary antiretroviral regimens.