The incidence of Kaposi sarcoma among injection drug users with AIDS in the United States.

Some studies report increased prevalence of human herpesvirus 8 (HHV-8), the causative agent of Kaposi sarcoma (KS), among injection drug users (IDUs), suggesting that HHV-8 may be transmitted through blood-borne or other exposures common in this population. Since an elevated HHV-8 prevalence in IDUs would likely lead to increased KS incidence, KS incidence was studied in IDUs and non-IDU's with AIDS. AIDS-related KS cases were identified using linked US AIDS and cancer registry data for 25,891 women, 47,782 heterosexual men, and 90,616 men who have sex with men (MSM). KS arose in 7099 persons with AIDS. KS incidence was highest for MSM (5.7 per 100 person-years), substantially lower for heterosexual men (0.7 per 100 person-years), and lowest for women (0.4 per 100 person-years). After adjustment for age, race, registry location, and year of AIDS onset, relative risks for KS associated with injection drug use were 1.3 (95% CI, 0.9-1.8) among women, 1.1 (0.7-1.6) among heterosexual men, and 0.9 (0.8-0.9) among MSM. It is concluded that injection drug use was not associated with an increased risk of AIDS-related KS. Thus, these data suggest that IDUs' risk of acquiring HHV-8, through needle sharing or other behaviors related to injection drug use, is low.