Objective: To evaluate the ability of serum levels of 90K, previously reported as a progression marker of human immunodeficiency virus infection, to predict the future rate of CD4 lymphocyte decline.
Design: Retrospective analysis of data from outpatients enrolled in a multi-institutional study.
Patients: One hundred five human immunodeficiency virus-positive intravenous drug users who had at least six serial CD4 lymphocyte measurements and starting CD4 levels of 200 x 10(6) cells/L or higher.
Main outcome measure: Rate of CD4 lymphocyte decline.
Results: During a median follow-up of 28 months (range, 20-36 months), the estimated loss of CD4 cells in the whole patient population was 3.4 x 106 cells/L per month (P = .0045). Subjects who were on zidovudine treatment at study entry showed an average loss of 3.8 x 10(6) cells/L per month, significantly higher than in untreated subjects (P = .02), but similar to the loss observed for those requiring initiation of treatment during the course of the study. At baseline, 56 subjects had 90K levels of 10 microg/mL or less, and 49 had more than 10 microg/mL. The rate of CD4 decline in the high-90K group was approximately 5 x 10(6) cells/L per month (P < .0015), whereas in the low-90K group it was not different from zero (P = ns). No difference emerged in the rate of CD4 decline when subjects were stratified according to baseline 90K levels and zidovudine treatment, beta2-microglobulin, or neopterin serum levels.
Conclusion: 90K serum levels are predictive of CD4 decline.