Objectives: To evaluate temporal trends of Kaposi's sarcoma (KS) and of the KS-related human herpesvirus (HHV-8) among homosexual men who seroconverted for HIV between 1984 and 1997.
Methods: The study participants were 387 homosexual men. Changes over a period of time were assessed by estimating KS incidence rates per 1000 person–years for the periods 1984–1989, 1990–1992, 1993–1995, and 1996–1997. The proportional incidence of KS as the AIDS-defining disease for the same periods was also calculated. To evaluate a cohort effect of calendar period, Kaplan–Meier curves were used to estimate the risk of KS by period of HIV seroconversion [i.e. before 1990 (median year of seroconversion) versus later]. Relative hazards for the four periods were estimated using competitive-risks models. We also estimated HHV-8 seroprevalence over the study period.
Results: Forty-eight participants developed KS. Between 1984 and 1995, the incidence rate of KS per 1000 person–years increased from 3.9 to 32.8, whereas the proportional incidence decreased from 33.3 to 24.3%. The risk of developing KS after HIV seroconversion did not change when comparing the seroconversion periods (i.e. before 1990 versus later). HHV-8 seroprevalence also remained stable. The rates of KS and the relative hazards dramatically decreased after 1995.
Conclusions: Although KS incidence rates increased up to 1995, the proportional incidence decreased, due to the higher increase in rates of other AIDS-defining diseases. The finding that the risk of developing KS after HIV seroconversion remained stable over time is consistent with the stable trend of HHV-8 seroprevalence. The dramatic decrease in KS incidence rates after 1995 coincides with combined antiretroviral therapy.
From the aAIDS & STD Unit, Laboratory of Epidemiology and Biostatistics, and Laboratory of Virology, Istituto Superiore di Sanità, the bIstituto di Ricovero e Cura a carattere Scientifico (IRCCS) L. Spallanzani, the cDepartment of Infectious Diseases, University Tor Vergata, the dIRCCS San Gallicano, Rome, the eIRCCS Maggiore Hospital, Milan, the fInfectious Disease Division, S. Orsola Hospital, University of Bologna and the gInfectious Disease Division, Amedeo di Savoia Hospital, Turin, Italy. *See Appendix.
Received: 25 November 1999;
revised: 7 March 2000; accepted: 16 March 2000.
Sponsorship: The study was supported by a grant from ‘Progetto Ricerche AIDS', Istituto Superiore di Sanità, Ministry of Health.
Correspondence to Dr Giovanni Rezza, AIDS and STD Unit, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy. Tel: +39 06 4938 7209 or 7211; fax: +39 06 4938 7210; e-mail: email@example.com