Evaluation of total lymphocyte count (TLC) as a surrogate marker for CD4 count in HIV-positive patients for resource-limited settings

Abstract

Context: The immunity in HIV-infected patients becomes low due to involvement of CD4 cells. The single best predictor of AIDS onset identified is the percentage or absolute number of circulating CD4+ T cells. However, providences in resource-constraint settings may not have access to this laboratory measurement, or its cost may be prohibitive resulting in the need for an alternative, surrogate marker. Hence, total lymphocyte count (TLC) was evaluated as a probable surrogate marker for CD4 count in this study. Aims: To evaluate the correlation of CD4 counts with the TLC for predicting the progression of HIV infection, and to determine a range of TLC cut-offs for predicting CD4 count <200 cells/μl, which is important for the initiation of antiretroviral therapy (ART) and opportunistic infection (OI) prophylaxis. Settings and Design: This study was conducted in the Department of Microbiology at Government Medical College, Aurangabad. Materials and Methods: A total of 250 HIV-positive patients were included in the study. Their Complete Blood count and CD4 count were measured and the TLC was computed. Statistical Analysis Used: SPSS software version 10.0. Results: A positive correlation between TLC and CD4 count was observed in our study, highlighting the role of this surrogate marker in resource-limited settings. Further, a TLC cut-off of ≤1700 cells/μl was found to be the best predictor for a CD4 count <200 cells/μl. Conclusions: A general correlation between the surrogate marker TLC and expensive CD4 counts could be elicited for the population under study. A TLC cut-off of ≤1700 cells/μl was the best predictor of CD4 count <200 cells/μl. This study demonstrates the ability of TLC, whether used as a continuous or dichotomous data, to predict CD4 count or a CD4 count <200 cells/μl, respectively.

Keywords

• CD4
• HIV
• surrogate marker
• total lymphocyte count