ArticlesSexual transmission of HIV-1 among injection drug users in San Francisco, USA: risk-factor analysis
Introduction
A large proportion of new HIV-1 cases in the USA are injecting drug users (IDUs).1 HIV-1 seroconversion of IDUs is mainly associated with injection-related risk factors.2, 3, 4, 5, 6 However, few seroconversion studies have been done since 1992 and in only two was an association seen between sexual risk factors and seroconversion.5, 6 Researchers commonly concentrate on injection-related risk factors and ignore sexual risk.7 In comparison with other US cities, HIV-1 prevalence among IDUs in San Francisco is moderate8 and has been stable at 10–14% since 1987.9, 10 HIV-1 prevalence among men who have sex with men in this city is high (30%).11 In San Francisco, HIV-1 incidence among IDUs in methadone clinics in the late 1980s was 1·9%,5 which was similar to an estimate for 15 other US cities at that time,4 and to another for 17 US cities in the mid-1990s (1·5%).12 Estimates of HIV-1 incidence in San Francisco for men who have sex with men are also similar to those of IDUs (1·2–2·8%).13, 14
San Francisco has adopted a harm-reduction philosophy15 for prevention of HIV-1 in IDUs, which started with community-health outreach programmes in 1985, so-called bleach and teach programmes in 1986, a syringe-exchange programme in 1988, and a policy of drug treatment on demand in 1997. Harm-reduction programmes are controversial in the USA, because workers help drug users to reduce risks whether they intend to enter drug treatment or not. These programmes have reduced injection-related risks even in regions where they are illegal.16 Few harm-reduction programmes in San Francisco have attempted to reduce sexual risk.
We assessed data from the Urban Health Study to establish risk factors for HIV-1 seroconversion among street-recruited IDUs.
Section snippets
Recruitment
Active IDUs were recruited for the Urban Health Study in three inner-city communities in San Francisco from 1986, and in a fourth from 1996. 6-monthly surveys included 170–250 IDUs in each community. We assessed data from 23 surveys done from 1986 to 1998. Respondents were recruited in natural settings with targeted sampling methods.17 Communities selected had high concentrations of IDUs according to drug-treatment admission data, police arrest data, direct observation, and earlier ethnographic
Results
We did 13 099 interviews and HIV-1-antibody tests. We identified 6115 different participants, of whom 2120 took part more than once. 1865 individuals were eligible for the case-control study. Mean (SD) number of observations per eligible person was 4·0 (2·8). 70 participants were classed as cases, of whom nine were excluded. The median observation time of the nine excluded seroconverters was 5·5 years (range 3·5–9·0). We excluded two cases for whom controls could not be found and one whose sex
Discussion
Our results show that the main risk factors for IDUs are sexual behaviours. The strongest predictor of HIV-1 seroconversion for men was having sex with men, whereas among women the strongest predictor was trading sex for money. These risk factors were reported by 53% of seroconverters. Strathdee and colleagues19 also showed that sexual risks among IDUs were associated with seroconversion. These results suggest that HIV-1 prevention should be concentrated on sexual risk among IDUs.
The results of
References (40)
- et al.
Randomised, controlled, community-level HIV-prevention intervention for sexual-risk behaviour among homosexual men in US cities. Community HIV Prevention Research Collaborative
Lancet
(1997) - et al.
Validity of self-reported drug use among injection drug users recruited through street outreach
Eval Prog Plan
(1994) The estimated prevalence and incidence of HIV in 96 large US metropolitan areas
Am J Public Health
(1996)- et al.
The harm reduction approach and risk factors for human immunodeficiency virus (HIV) seroconversion in injecting drug users, Amsterdam
Am J Epidemiol
(1992) - et al.
Incidence and risk factors of HIV infection: a prospective study of seronegative drug users from Milan and northern Italy, 1987–1989
Epidemiology
(1990) - et al.
Risk factors for human immunodeficiency virus seroconversion among out-of treatment drug injectors in high and low seroprevalence cities
Am J Epidemiol
(1995) - et al.
HIV seroconversion in intravenous drug users in San Francisco, 1985–90
AIDS
(1994) - et al.
Differences in risk factors for human immunodeficiency virus type 1 seroconversion among male and female intravenous drug users
Am J Epidemiol
(1993) - et al.
Drug injecting, rapid HIV spread, and the ‘risk environment’: implications for assessment and response
AIDS
(1999) - et al.
HIV seroprevalence among street-recruited injecting drug and crack cocaine users in 16 US municipalities
Am J Public Health
(1998)
Trends in risk behaviors and HIV seroprevalence in heterosexual injection drug users in San Francisco, 1986–1992
J Acquir Immune Defic Syndr Hum Retrovirol
Risk factors among IDUs who give injections to or receive injections from other drug users
Addiction
HIV prevalence and incidence in San Francisco
Seroconversion issues among out-of-treatment injection drug users
J Psychoactive Drugs
Recent increases in HIV seroconversion among repeat anonymous testers in San Francisco
AIDS
Estimation of human immunodeficiency virus (HIV) seroincidence among repeat anonymous testers in San Francisco
Am J Epidemiol
Harm reduction: a framework for incorporating science into drug policy
Am J Public Health
Use of an illegal syringe exchange and injection-related risk behaviors among streetrecruited injection drug users in Oakland, California, 1992–1995
J Acquir Immune Defic Syndr Hum Retrovirol
Targeted sampling: options for the study of hidden populations
Soc Problems
Interpretive criteria used to report western blot results for HIV-1-antibody testing–United States
MMWR Morb Mortal Wkly Rep
Cited by (314)
Impact of a high-volume overdose prevention site on social and drug disorder in surrounding areas in San Francisco
2023, Drug and Alcohol DependenceA randomized clinical trial evaluating the impact of counselor training and patient feedback on substance use disorder patients' sexual risk behavior
2022, Journal of Substance Abuse TreatmentTrans-ancestral fine-mapping of MHC reveals key amino acids associated with spontaneous clearance of hepatitis C in HLA-DQβ1
2022, American Journal of Human GeneticsEvaluation of the scale-up of HIV testing among people who inject drugs in Scotland in the context of an ongoing HIV outbreak
2021, International Journal of Drug PolicySexual-risk reduction following the referral of syringe exchange registrants to methadone maintenance: Impact of gender and drug use
2021, Journal of Substance Abuse Treatment