Measures of human immunodeficiency virus (HIV) community viral load and HIV incidence among people who inject drugs

Abstract

PurposeTo evaluate the measures of community human immunodeficiency virus (HIV) viral load (VL) and the association with HIV incidence among people who inject drugs (PWID). MethodsData were from 1986 to 1999 Urban Health Study conducted among PWID in the San Francisco Bay Area. Extant measures of community VL use mean VL among HIV + study participants, not accounting for the proportion of HIV- individuals. We compared the strength of the associations between HIV incidence and the traditionally measured mean community VL and a new prevalence-adjusted community VL, calculated by dividing the sum of VL among HIV + participants by the total participants irrespective of HIV status. ResultsMean community VL was not correlated with HIV incidence in this sample of PWID (rs = 0.32, P = .28). However, prevalence-adjusted community VL was strongly correlated with HIV incidence (rs = 0.69, P = .009). Nested complimentary log-log linear models indicated that increases in community VL and prevalence-adjusted community VL were both associated with HIV incidence, but prevalence-adjusted community VL was a more sensitive measure (hazard ratio = 1.28, P = .038 and hazard ratio = 3.29, P < .001, respectively). ConclusionsThe effect of community VL on HIV incidence may be stronger than previously reported. Future studies of community VL surveillance should consider accounting for the prevalence of HIV using a prevalence-adjusted community VL measure.