DIFFERENTIAL SURVIVAL OF PATIENTS WITH AIDS ACCORDING TO THE 1987 AND1993 CDC CASE DEFINITIONS

Objective.-To evaluate the impact of the 1993 Centers for Disease Cont rol and Prevention (CDC) revised classification system for human immun odeficiency virus and expanded surveillance case definition for acquir ed immunodeficiency syndrome (AIDS) on the number of cases and on surv ival of patients with AIDS. Design.-Retrospective analysis of data fro m a prospective cohort study of patients treated with zidovudine. Pati ents.-A total of 3515 patients enrolled in the Italian National Regist ry of Zidovudine-Treated Patients between July 1987 and December 1991 were analyzed. Main Outcome Measures.-Numbers and survival probability estimates (using the Kaplan-Meier method) for patients satisfying the 1993 CDC case definition compared with patients fulfilling the 1987 C DC classification. Multiple regression analysis was also used to analy ze the combined effect of independent variables on survival. Results.- According to the new classification system, the number of AIDS cases i n the study population would increase by 188%. While the median surviv al of patients meeting the 1987 definition was 24 months, at the end o f 57 months 53% of patients meeting the 1993 definition were still ali ve. Among the patients meeting the laboratory criteria for AIDS diagno sis using the new definition (CD4+ lymphocyte count <0.20x10(9)/L [200 /muL]), the presence of an AIDS-defining illness was a strong independ ent predictor of death. Conclusions.-The application of the new defini tion results in a considerable increase in the number of cases. Surviv al for patients classified according to the 1993 definition is much lo nger than for those classified with the 1987 definition. Clinical stat us plays a major role in predicting survival outcome among patients wh ose CD4+ lymphocyte counts meet the new case definition.