Estimation of survival after AIDS diagnosis: CD4 T lymphocyte count versus clinical severity

We compared the relative contribution to estimating survival after AIDS diagnosis of a clinical severity measure, the Severity Index for Adults with AIDS (SIAA), and laboratory values at AIDS diagnosis that are often used prognostically. Three SIAA categories were defined from the first AIDS-defining condition and the most severe complication within 3 months. We studied 421 Italian patients surviving ≥ 3 months after AIDS diagnosis. Survival curves for laboratory measures grouped by quartile showed poorest survival for CD4 count < 100/μl, hemoglobin < 8 g/dl, total lymphocyte count < 400/μl, and albumin < 3 g/dl. Adjusting for demographics and zidovudine therapy, the estimated hazard of death was 2.4 (95% CI, 1.6–3.5) for CD4 counts < 100/μl versus higher counts and 4.9 (95% CI, 3.0–7.8) for the most versus the least severe SIAA category. SIAA offered greater prognostic discrimination than CD4 count at AIDS diagnosis.