Abstract

MODELING OF HIV/AIDS SURVIVAL AND STAGING USING SURROGATE MARKERS

*P. Venkatesan

Abstract

For staging and survival, guiding treatment decisions and evaluating effectiveness of therapy of HIV/AIDS, CD4 testing is used as the gold standard. It is expensive to use in resource settings and there is a need for a less expensive surrogate marker to replace it. Several markers were studies in the past and Total Lymphocyte counts (TLC) was one the most studied worldwide. Since TLC varies according to ethnic groups, there is a need to assess the suitability for a particular population. This study sought to assess the suitability of TLC as a surrogate marker for CD4 count in Indian population. The data for the study was taken from 395 patients who were referred to a HIV clinical trial and tested for both CD4 count and TLC. The sensitivity, specificity and predictive values of various cut-off points of TLC were calculated. The decision theory based analysis was also carried out for various CD4 counts and their corresponding TLCs. The sensitivity and specificity of TLC in classifying HIV and AIDS based on CD4 as gold standard were about 50% and 95% respectively. Hence we conclude the TLC seems to be not an adequate marker for HIV/AIDS classification in Indian population as the sensitivity was very low.

Keywords: TLC, CD4 count, HIV, AIDS, biomarker, Sensitivity, Specificity.