The 6-month assessment of the response to antiretroviral therapy (ART) is a critical step. In sub-Saharan Africa, few people have access to plasma viral load (VL) measurement. We assessed the gain or loss in BMI (ΔBMI), alone or in combination with the gain or loss in CD4 (ΔCD4), as a tool for predicting the response to ART at 6 months.
In a cohort of 622 adults in Abidjan, we calculated the sensitivity, specificity and predictive values of ΔBMI and ΔCD4 for treatment success, with VL undetectability (<300 copies/ml) as gold standard.
After 6 months of ART, the median ΔBMI was +1.0 kg/m2 (interquartile range [IQR] +0.0; +2.1), the median ΔCD4 was +148/mm3 (IQR +54; +230) and 84% of patients reached VL undetectability. The distribution of ΔBMI was similar among patients who reached VL undetectability and those who did not (median +1.06 vs. +0.99 kg/m2, p = 0.51). With increasing ΔBMI, the specificity of ΔBMI for treatment success increased but its sensitivity decreased and its positive predictive value remained stable around 85%. All results remained similar when combining ΔBMI with ΔCD4 and when stratifying by groups of baseline BMI or CD4.
In settings where VL measurement is not available, a high BMI gain should not be interpreted as reflecting virological success, even when combined with a high CD4 gain. In our population, most patients with detectable VL were probably sufficiently adherent to reach significant BMI and CD4 gain but insufficiently adherent to reach VL suppression.