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Objective: Sex exchange is a well-established risk factor for HIV infection. Little is known about how correlates of sex trade differ by biologic sex and whether length of homelessness is associated with sex trade. We conducted a cross-sectional study among a sample of 1,148 homeless and marginally housed individuals in San Francisco to assess correlates of exchanging sex for money or drugs. Key independent variables included length of homelessness; use of crack, heroin or methamphetamine; HIV status; and sexual orientation. Analyses were restricted by biologic sex. In total, 39% of women and 30% of men reported a lifetime history of sex exchange. Methamphetamine use and greater length of homelessness were positively associated with a history of sex trade among women, while heroin use, recent mental health treatment, and homosexual or bisexual orientation were significantly associated with sex trade for men. Crack use was correlated with sex trade for both genders. Correlates of sex trade differ significantly according to biologic sex, and these differences should be considered in the design of effective HIV prevention programs. Our findings highlight the critical need to develop long-term services to improve housing status for homeless women, mental health services for homeless men, and drug treatment services for homeless adults involved in sex work.
Sex trade is a well known risk factor for HIV infection.1–3 Correlates of sex trade reported in the literature include homelessness,4–6 illicit drug use,4,5,7 African American race,8,9 female gender,5,8 prior criminal offense,6,9 prior mental health hospitalization,4 and HIV infection.7 Given that many of these variables are associated with poor overall health, understanding points of overlap could offer insight into improved health delivery models and targeted health interventions.
Gender is an important factor in the context of sex exchange,10,11 yet few studies have conducted parallel analyses of men and women from the same population. Similarly, while homelessness has been identified as an important predictor of sex trade, there is little data on whether length of time homeless is associated with sex trade. We therefore set out to assess: 1) factors associated with sex trade among a sample of homeless and marginally housed adults in San Francisco and 2) whether correlates of sex trade differ by biological sex in this population.
Between January 1999 and April 2000, a mobile outreach team recruited individuals from all large homeless shelters, free food programs providing more than 100 meals per day, and a random sample of low-income hotels in three neighborhoods of San Francisco selected with a probability proportional to size, as previously reported.12
Structured interviews included topics pertaining to socio-demographic factors; history of sex trade, drug and alcohol use; sexual behaviors; and health care utilization. Each participant also underwent an HIV test and was reimbursed $15 for their participation. The Committee on Human Research at University of California, San Francisco, approved all study procedures.
The primary outcome was a history of sex trade, which was defined as having ever given sex in exchange for money or drugs. Covariates for this study included age (categorized at natural breaks in the data), race (white or non-white), education (> or ≤ high school diploma), having any children, any lifetime heroin use, any lifetime cocaine use, any lifetime methamphetamine use, length of lifetime homelessness (sleeping on the street or in a shelter), problem drinking (greater than an average of 14 drinks per week for men, or seven drinks/week for women13), HIV status, sexual orientation (straight versus homosexual or bisexual), and mental health treatment over the past 12 months.
Multiple logistic regression, clustered by recruitment venue, was used to determine independent factors associated with sex trade and the final model was estimated using a backward stepwise approach. Type I error was set at .05. Analyses were restricted by gender.
Among 1,175 biological men and women recruited, 1,148 (249 women and 899 men) received interviews that included questions regarding sex trade history. There were less than 2.4% missing data on all variables. Approximately 70% of both genders had graduated high school, and 28% of women and 34% of men in the sample were Caucasian. The median age was 44.6 for women and 46.3 for men. Thirty-two percent of men and 33% of women self-identified as bisexual or homosexual. Approximately 40% of both genders had ever used heroin, 24% were problem drinkers, and 67% had ever used crack. The majority of participants (>65%) had been homeless for less than 5 years in their lifetime. Significant demographic differences between men and women included that more women had children (37% versus 17%, p < .01), more men had used methamphetamine (53% versus 40%, p < .01), and HIV prevalence was higher among men (15% versus 10%, p < 0.05). In total, 39% of women and 30% of men had engaged in sex trade, and women had 50% higher odds of reporting sex trade compared to men (95% Confidence Interval (CI) = 1.05–2.07).
There were several important differences in correlates of sex trade between genders (Table 1). In adjusted analyses, a history of methamphetamine use and more time homeless were positively associated with a history of sex trade among women, while heroin use, recent mental health treatment, and homosexual or bisexual orientation were significantly associated with sex trade for men. Crack use was correlated with sex trade for both genders: Men who had used crack had less than three times the odds of reporting sex trade (OR = 2.77; CI = 2.23–3.80), while women who had used crack had ten times the odds of reporting sex trade (OR = 9.99; CI = 4.80–20.75).
In a sample of 1,148 homeless and marginally housed adults living in San Francisco, we found that nearly one third of men and over one third of women reported a history of sex trade and that the correlates of sex trade differed between men and women. Kilbourne et al.14 previously found that time homeless predicted sex trade among unstably housed women. Our data support this finding and also indicate that similar associations are not found among men, suggesting that the affect of time homeless on sex trade is specific to women. Considering that 9% of low income (but housed) women in San Francisco have previously reported a history of sex work,15 the 39% prevalence found here highlights the impact of homelessness on the risk of sex trade. Homelessness has also been associated with a myriad of other poor health outcomes among women including illicit drug use, having multiple sex partners, sexual assault, and worse physical and mental health.16,17 Our findings provide further support for the idea that housing is crucial for both the physical and psychological well being of homeless women.
Drug use was associated with sex trade for both women and men, but the drugs associated were different, namely heroin use for men and methamphetamine use for women. During the current time of heightened attention to methamphetamine use as a risk factor for HIV among men who have sex with men,18 our results highlight the need to maintain messages about heroin in prevention programs targeted to men, and to consider methamphetamine use as a possible co-factor for HIV transmission among women. Crack use was associated with sex exchange for both genders and is also an important risk factor for HIV transmission independent of its association with sex exchange. Our findings suggest that HIV prevention policies aimed at sex workers should simultaneously target crack and methamphetamine use by increasing access to stimulant treatment programs.
Findings in this paper should be interpreted within the limitations that the study was cross-sectional, that several of our independent variables were available in the recent time frame only, and that our study sample had over three times as many men compared to women. The major strengths of the study include a large data set on homeless and marginally housed adults, which allowed for comparisons between men and women on the same variables during the same time period. Our results highlight a continued need for women-specific housing services, men-specific mental health services, and drug (particularly stimulant) treatment for homeless adults involved in sex work.
This study was funded by the National Institutes of Health grants R01 DA15605, RO1 MH54907, and T32 MH19105.
Weiser, Dilworth, and Neilands are with the Center for AIDS Prevention Studies, University of California, San Francisco (UCSF), San Francisco, CA, USA. Cohen, Bangsberg, and Riley are with Epidemiology and Prevention Interventions (EPI) Center, Division of Infectious Diseases, San Francisco General Hospital, UCSF; Bangsberg is with the Positive Health Program, San Francisco General Hospital, UCSF.
The Epidemiology and Prevention Interventions Center, Positive Health Program and Center for AIDS Prevention Studies are programs of the UCSF AIDS Research Institute.