Abstract
OBJECTIVES: WHO recommends HIV viral load (VL) testing 6 months after antiretroviral therapy (ART) initiation and every 12 months thereafter, but cost prohibits routine, universal VL testing in many developing countries. We sought to devise a targeted approach to routine VL monitoring that could reduce cost and identify those at low risk for virologic failure (VF). METHODS: We analysed screening data from a clinical trial enrolling adults on ART in Malawi. We identified risk factors associated with VF and employed the Knill-Jones method to assign summary score identifying persons at lower risk for VF. RESULTS: Among 957 adults, prevalence of VF was 9.4%. Factors independently associated with VF included age <38 years (OR 3.44, 95% CI 2.01-5.89), ART duration >2.5 years (OR 2.98, 95% CI 1.79-4.96), ART adherence <95% (OR 1.76, 95% CI 1.06-2.94), CD4 count <200 cells/μl (OR 5.94, 95% CI 3.27-10.78), haemoglobin <13 g/dl (OR 2.76, 95% CI 1.70-4.50) and CD8 count >885 cells/μl (OR 2.10, 95% CI 1.28-3.44). Our VF prediction summary score included all factors above except CD8 count and was fairly accurate with validated area under receiver operating characteristic curve of 0.76. Implementation could reduce VL testing by 65%. CONCLUSION: A simple score incorporating age, ART duration and adherence, and CD4 count can accurately identify adults at low risk for VF in a sub-Saharan African setting. In areas with high ART utilisation and limited VL testing capacity, a targeted approach could optimise routine VL monitoring while identifying adults in need of alternate ART regimens.