THE EFFECT OF THE 1993 EUROPEAN REVISION OF THE AIDS CASE-DEFINITION IN ITALY - IMPLICATIONS FOR MODELING THE HIV EPIDEMIC

Objectives: To evaluate the effect of the 1993 European AIDS definitio n on reducing pre-AIDS mortality and to what degree an earlier diagnos is can be made. Design: Prospective observational study. Methods: All patients diagnosed between January 1993 and December 1994 and reported to the National AIDS Registry from four Italian regions, who met only the new criteria for the 1993 case definition (AIDS-1993) were studie d. Follow-up of patients who did not eventually meet the 1987 definiti on (AIDS-1987), or had not died from other causes (pre-AIDS-1987 death ), was censored at the last available clinical visit before 1 April 19 96. We analysed the data using Kaplan-Meier nonparametric survival ana lysis and Cox proportional hazards model. Results: A total of 74 (4.1% ) individuals met only the new criteria. Of these, 49 (62.2%) were men , 42 (56.8%) had pulmonary tuberculosis, 22 (29.7%) had recurrent bact erial pneumonia, and 10 (13.5%) had cervical cancer. During followup, 35 (45.3%) individuals developed an AIDS-1987 disease, and 10 (13.5%) died without fulfilling the AIDS-1987 definition. Pre-AIDS-1987 death accounted for 22.2% (10 out of 45) of the subsequent outcomes observed prior to 1 April 1996. Using Kaplan-Meier technique, we estimated tha t after 9.8 months 50% of these individuals were diagnosed with AIDS-1 987 disease, or died without such a diagnosis. Individuals with lower CD4+ count at the time of the AIDS-1993 diagnosis progressed more rapi dly to AIDS-1987 than those with a higher count. In contrast, pre-AIDS -1987 mortality was strongly associated with injecting drug use, where as no association was found with CD4+ count. Conclusions: Approximatel y 50% of individuals with one of the three new AIDS-defining diseases will develop an AIDS-1987 disease or will die within 1 year. Time from AIDS-1993 to AIDS-1987 disease is strongly associated with CD4+ count at diagnosis. AIDS-1993 diagnosis reduced the pre-AIDS-1987 mortality in injecting drug users. Furthermore, approximately 20% of individual s diagnosed with AIDS-1993 disease are expected to die without develop ing an AIDS-1987 disease. These data should be useful for correcting t he AIDS incidence curve in Europe for the effect of the changes in the AIDS definition.