CORRELATION BETWEEN TOTAL AND CD4 LYMPHOCYTE COUNTS IN HIV-INFECTION - NOT MAKING THE GOOD AN ENEMY OF THE NOT SO PERFECT

The aim of this study was to assess the correlation and average cost o f total lymphocyte count compared with CD4 count as a broad estimate o f immunosuppression in HIV-1 infected individuals. Spearman's partial rank correlation were calculated between total lymphocyte count, absol ute CD4 count and CD4 per cent stratified by stage of HIV-1 infection for routinely collected samples. Data were collected prospectively fro m a T cell-subset register combined with clinical data obtained retros pectively from case notes of HIV-infected patients managed at St Mary' s Hospital, London 1982-1991. Costing data were obtained through a sur vey of the departments of haematology and immunology (1989/90 prices). The correlation between 1534 paired absolute lymphocyte count and CD4 lymphocyte count was found to be high (R=0.76). When analysed by stag e of HIV infection, the correlation increased from R=0.64 for asymptom atic patients, to R=0.72 for patients with symptomatic non-AIDS HIV in fection and R=0.73 for AIDS patients. Correlations between absolute ly mphocyte count and CD4 per cent were considerably weaker: R=0.41 all p aired counts; R=0.32 for asymptomatic patients; R=0.25 for symptomatic non-AIDS patients; R=0.32 for AIDS patients. Average cost was pound 8 per full blood count compared with pound 38 per T-cell subset analysi s. The high correlation between total and CD4 lymphocyte counts, espec ially for patients with symptomatic I-W disease, demonstrates the suit ability of the use of total lymphocyte count in the absence of CD4 cou nts. Given the considerably lower prices of total lymphocyte counts co mpared with T-cell subset analysis, this is particularly relevant for developing countries.