Evaluating total lymphocyte count as a surrogate marker for CD4 cell count in the management of HIV-infected patients in resource-limited settings: a study from China.

OBJECTIVE: To evaluate the correlation of total lymphocyte count (TLC) and CD4 cell count and the suitability of TLC as a surrogate marker for CD4 cell count of HIV-infected patients in China. METHODS: Usefulness of TLC as a surrogate marker for a CD4 cell count <350 cells/mm(3) for HIV-positive patients in China was evaluated by 977 pairs of TLC and CD4 cell count from 977 outpatients. The result was then validated by a literature review which was conducted on 9 relevant articles. Further investigation using the 977 pairs of TLC and CD4 cell count data was done to determine a TLC threshold for predicting a CD4 cell count <500 cells/mm(3). Correlation and receiver operating characteristic (ROC) analysis were performed for both CD4 cell counts, and the sensitivity and specificity were computed. RESULTS: Good correlation was noted between TLC and CD4 count (r = 0.60, 95% CI, 0.56-0.64). TLC obtained a relatively high diagnostic performance (area under ROC curve, 0.80) for predicting a CD4 cell count <350 cells/mm(3), with a sensitivity of 0.65 (95% CI, 0.61-0.68) and a specificity of 0.80 (95% CI, 0.75-0.85) at the TLC threshold of 1570 cells/mm(3). The literature review suggested that for a CD4 cell count <350 cells/mm(3), the optimal TLC threshold was 1500 cells/mm(3), which was similar to the figure presented in this observational study. As for predicting a CD4 cell count