Rapid declines in total lymphocyte counts and hemoglobin concentration prior to AIDS among HIV-1-infected men.

OBJECTIVE To describe temporal patterns in total lymphocyte count (TLC) and hemoglobin (Hgb) concentration during HIV infection and relate these patterns to changes in other markers and to clinical disease. DESIGN Prospective cohort study. METHODS Longitudinal trajectories of total lymphocyte count and hemoglobin from men in the Multicenter AIDS Cohort Study were studied by applying, to each individual, a segmented regression model to capture changes in marker trajectories at an inflection point. The estimated slope of these markers before and after the inflection point were examined to determine whether those with AIDS onset could be distinguished from those remaining free of AIDS through the use of receiver operating characteristic (ROC) curves. RESULTS Prior to the estimated inflection points, TLC and Hgb marker slopes were distributed around zero in all men; afterwards, those who developed AIDS showed rapid declines in both markers. A TLC decline greater than 10% and Hgb decline greater than 2.2% was present in over 77% of HIV-positive men who developed AIDS but only 23% of HIV-positive men who did not. Among those who developed AIDS, rapid declines in TLC and Hgb began as CD4+ cell counts fell from 350 to 200 x 106 cells/l and preceded clinical AIDS by a median of about 1.6 years. CONCLUSIONS Both TLC and Hgb showed a period of stability, which was followed by a rapid decline beginning shortly before the onset of AIDS. These results suggest that TLC and Hgb might be useful for monitoring disease progression in resource-limited settings.