Abstract

CD4 count testing is perceived to be an affordable strategy to diagnose treatment failure on first-line antiretroviral therapy. We hypothesize that the superior accuracy of viral load (VL) testing will result in less patients being incorrectly switched to more expensive and toxic second-line regimens. Using data from a drug resistance cohort, we show that CD4 testing is approximately double the cost to make 1 correct regimen switch under certain diagnostic thresholds (CD4 = US $499 vs. VL = US $186 or CD4 = US $3031 vs. VL = US $1828). In line with World Health Organization guidelines, our findings show that VL testing can be both an accurate and cost-effective treatment monitoring strategy.