DIFFERENCES IN RISK-FACTORS FOR HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 SEROCONVERSION AMONG MALE AND FEMALE INTRAVENOUS-DRUG-USERS

To examine sex-specific risk factors for human immunodeficiency virus (HIV) type 1 seroconversion among intravenous drug users, the authors conducted a nested case-control study in Baltimore, Maryland, from 198 8 to 1992 comparing 146 seroconverters and 539 HIV seronegative contro ls. Controls were matched on sex, race, date of study entry, and durat ion of follow-up. Risk factor data were obtained from interviews condu cted at the first seroconversion visit for the case and the closest vi sit for the corresponding seronegative control. Since test results wer e not available until several weeks after interview, both interviewers and participants were unaware of seroconversion status at the time of interview. When data were analyzed using conditional logistic regress ion techniques, the variables which were significantly associated with seroconversion among male intravenous drug users included age less th an 35 years, a sexually transmitted disease within the past 6 months, lifetime history of syphilis, and current intravenous drug use with an abscess at the injection site. Among women, only a history of three o r more sex partners was positively associated with seroconversion and having a biological child under age 18 years was inversely associated with HIV seroconversion. Although the small sample size may have limit ed the ability to ascertain differences in risks of seroconversion amo ng males and females, these data suggest that sexual transmission cont ributes to HIV infection among intravenous drug users, especially wome n.