PREDICTING SURVIVAL IN AIDS - REFINING THE MODEL

We tested the validity of a previously-published AIDS staging system b y examining AIDS-defining diseases (ADDs) and CD4 counts as prognostic factors for survival of the 248 AIDS patients in the Edinburgh City H ospital Cohort, of whom 56% were injecting drug-users (IDUs). Cox regr ession was used to model the proportionality of risk of death as the C D4 count declined and more ADDs were experienced, and dependence upon post-AIDS treatment. Using the system of Mocroft et at (Lancet 1995; 3 46:12-17) to grade severity, our data were well enough modelled, but w e suggest: (i) regrading of HIV dementia (RR 3.9, 95% CI 2.5-6.0), mai nly attributed to the drug users, to a very severe ADD (ii) reduction in risk from zidovudine (RR 0.7, 95%) CI 0.5-1.0) during AIDS follow-u p for patients starting treatment at or after AIDS diagnosis; (iii) im proved management of first mild ADDs (from 1987-89 to 1994-95: 40% red uction in IDUs appearing with mild index diseases, and an approximate three-fold reduction in risk associated with a mild ADD). This study s upports previous findings on the significance of ADDs and lowest CD4 c ount in predicting the lifetime of AIDS patients.