Early HIV viral load determination after initiating first-line antiretroviral therapy for indentifying patients with high risk of developing virological failure: data from a cohort study in a resource-limited setting.

OBJECTIVES: To evaluate the performance of a single determination of HIV viral load (VL) 6-12 months after starting antiretroviral therapy (ART) for identifying patients who will subsequently develop virological failure.
METHODS: We selected HIV-infected patients with at least two VL determinations after 6 months of ART from an HIV cohort study in India. Patients were divided in two groups depending on whether the first VL was below (Group 1) or above (Group 2) 1000 copies/ml. Cut-off for virological failure was defined according to World Health Organization recommendation (>5000 copies/ml).
RESULTS: The study included 584 patients and 560.1 person-years of follow-up. Of all virological failures, 83% were diagnosed at the first VL determination. The cumulative incidence of virological failure after 1 and 2 years since the first VL was 0.9% [95% confidence interval (CI), 0.3-2.7] and 1.7% (95% CI, 0.6-5), respectively, for Group 1, and 58.2% (95% CI, 47-69.7) and 63.1% (95% CI, 49.8-76.4), respectively, for Group 2. Compared with Group 1, patients from Group 2 had a hazard ratio for virological failure of 78.3 (95% CI, 27.8-220.2).
CONCLUSIONS: A single VL determination after 6 months of ART was able to identify patients with high risk of virological failure.