Abstract
BACKGROUND: Viral load (VL) monitoring is standard of care in HIV-infected persons initiated on antiretroviral therapy (ART). We evaluated the predictive value of VL measurements at 6 and 12 months after initiation of firstline ART to estimate the future risk of virologic failure (VF). METHODS: HIV-infected persons with VL measurements at 6 and 12 months post-ART initiation and at least 2 additional VL measurements thereafter were assessed for risk of future VF, defined per World Health Organization guidelines. VL at 6 or 12 months post-ART was categorized into <400, 400-1000, 1001-2000, and >2000 copies/mL. Cox proportional hazard models were used to compare VF incidence associated with 6-month, 12-month, and a composite of 6- and 12-month VL prediction indicators. RESULTS: Overall, 1863 HIV-infected adults had a 6- and 12-month VL measurement, and 1588 had at least 2 additional VLs thereafter for predicting future VF. The majority (67%) were female (median age: females 33 years and males 37 years). At 12 months post-ART, 90% had VL<400 copies/mL (cumulative incidence of VF at 1.5%), 3% had 400-1000 copies/mL (VF 12%), 2% had 1001-2000 copies/mL (VF 22%), and 5% had >2000 copies/mL (VF 71%). The predictive value of the 12-month VL measurement was comparable to the composite of both the 6- and 12-month VL measurements and better than the 6-month VL measurement. CONCLUSIONS: At 12 months after ART initiation, 90% of patients were virally suppressed with a low likelihood of future VF. VL measurement at 12 months post-ART initiation predicts risk of VF and could inform differentiated virologic monitoring strategies.