Ethnicity and discordance in plasma HIV-1 RNA viral load and CD4+lymphocyte count in a cohort of HIV-1-infected individuals

Background: Guidelines for commencing therapy for HIV infection have been based upon HIV-1 RNA and CD4 lymphocyte thresholds. The influence of confounding factors such as gender, ethnicity and co-infections is unproven. Objectives: To analyse ethnic discordance in plasma HIV-1 viral load (VL) and CD4+ count and its potential clinical significance in Black and Caucasian groups. Study design: Retrospective, cross-sectional, observational study of 537 antiretroviral naive HIV-1-positive individuals attending two East London clinics. Baseline data were obtained from individuals who registered at the clinic from November 1996 to August 1999. An analysis was performed comparing ethnic differences in plasma HIV-1 VL, CD4+ count, CD8+ count, co-infections, CDC disease category, AIDS-defining illnesses and mode of transmission. Results: Plasma HIV-1 VL was significantly lower in Blacks (4.5 copies/ml versus 4.7 copies/ml; P < 0.05) despite lower baseline CD4+ counts and similar rates of disease progression to Caucasian groups. This association remained for patients with less advanced disease after stratification for CD4+ count (CD4+ 200-500, VL 4.5 copies/ml versus 4.7 copies/ml, P < 0.01; CD4 + > 500, VL 3.4 copies/ml versus 4.3 copies/ml, P < 0.001) and disease category (non-AIDS, 4.4 copies/mI versus 4.7 copies/ml; P < 0.005). On multivariate analysis, the association persisted following adjustment for gender, age, co-infections, CD4+ count and mode of transmission. Conclusions: These results suggest that plasma HIV-1 VL is discordantly low in Black compared with Caucasian groups stratified for CD4+ count, in this cohort of antiretroviral naive HIV-1-positive individuals living in London. Although there are a number of possible explanations for this finding, it has considerable clinical relevance for the management of Black HIV-1-infected patients within UK, with significant implications for the decision about when to commence antiretroviral or immune-based therapies. (C) 2002 Elsevier Science B.V. All rights reserved.