IS THE HUMAN IMMUNODEFICIENCY VIRUS-RELATED KAPOSIS-SARCOMA EPIDEMIC COMING TO AN END - INSIGHTS FROM THE TRICONTINENTAL SEROCONVERTER STUDY

A decline in the proportion of Kaposi's sarcoma among AIDS cases since the 1980s has been attributed to changes in sexual behavior among hom osexual men and a decreasing exposure to a hypothesized Kaposi's sarco ma cofactor. Recent studies have shown that the incidence rate of Kapo si's sarcoma has remained relatively stable, which seems to argue agai nst the hypothesis of a declining exposure to the putative cofactor, T o examine this paradox, we evaluated the incidence of Kaposi's sarcoma , using Cox proportional hazard analyses, and per formed a simulation to compare incidences of different AIDS outcomes among 407 homosexual men with documented dates of seroconversion. Our data show that men wh o seroconverted early in the epidemic did not progress faster to Kapos i's sarcoma than men who seroconverted more recently, A lower incidenc e rate of Kaposi's sarcoma would be expected among the latter group if exposure to the hypothesized cofactor is decreasing over time, The pe rcentage of Kaposi's sarcoma among incident AIDS cases decreased over the years following seroconversion, but not over calendar time. This s tudy demonstrates that the decline in the proportion of Kaposi's sarco ma among AIDS cases should not be interpreted as a decline in the inci dence of Kaposi's sarcoma and that there is no evidence that a hypothe sized Kaposi's sarcoma cofactor is declining over calendar time.