CATEGORY OF EXPOSURE TO HIV AND AGE IN THE PROGRESSION TO AIDS - LONGITUDINAL-STUDY OF 1199 PEOPLE WITH KNOWN DATES OF SEROCONVERSION

Objectives-To determine whether rate of development of AIDS is affecte d by category of exposure to HIV and whether the more rapid developmen t found in older subjects persists for each exposure category. Design- Longitudinal study of people with known date of seroconversion to HIV. Setting-16 HIV treatment centres throughout Italy. Subjects-1199 peop le infected with HIV through use of injected drugs, homosexual sex, or heterosexual sex. Main outcome measures-AIDS as defined by 1987 defin ition of Centers for Disease Control (including and excluding neoplasm s) and by 1993 European definition.Results-225 subjects (18.8%) progre ssed to AIDS (Centers for Disease Control 1987 definition) during medi an follow up of 5.8 years. Univariate analyses showed more rapid progr ession to AIDS for older subjects compared with younger subjects and f or homosexual men compared with other exposure categories. The age eff ect was of similar size in each exposure category and in men and women . In a bivariate model with age and exposure categories simultaneously included as covariates, differences by exposure category disappeared for use of injected drugs and heterosexual sex compared with homosexua l sex (relative hazards 1.02 (95% confidence interval 0.71 to 1.45) an d 1.07 (0.70 to 1.64) respectively), while the age effect remained (re lative hazard 1.55 (1.32 to 1.83) for 10 year increase in age). Analys es using the other definitions for AIDS did not appreciably change the se results. Conclusions-There was no evidence of differences in rate o f development of AIDS by exposure category, while there was a strong t endency for more rapid development in older subjects for all three gro ups. This supports the view that external cofactors do not play major role in AIDS pathogenesis but that age is of fundamental importance.