Interpersonal and structural factors associated with receptive syringe-sharing among a prospective cohort of female sex workers who inject drugs

Aims: To determine the interpersonal and structural factors associated with receptive syringe sharing (RSS) among female sex workers who inject drugs (FSW-IDU), a group at high risk of HIV/hepatitis C virus (HCV) acquisition.

Design: Sex workers And Police Promoting Health In Risky Environments (SAPPHIRE) study, a prospective cohort study.

Setting: Baltimore, MD, USA PARTICIPANTS: One hundred and eighty FSW-IDU; mean age = 33 years, 77.1% white and 62.9% in a relationship/married.

Measurements: Surveys were conducted between April 2016 and February 2018. The main outcome was recent RSS (past 3 months). In addition to socio-demographic characteristics and drug use behaviors, we assessed factors at the interpersonal level, including injection practices, intimate partner and client drug use and exposure to violence. Structural-level factors included methods of syringe access.

Findings: Nearly all FSW-IDU used heroin (97.1%) or crack cocaine (89.7%). Recent RSS was reported by 18.3%. Syringes were accessed from needle exchange programs (64.6%), pharmacies (29.7%), street sellers (30.3%) or personal networks (29.1%). Some FSW-IDU had clients or intimate partners who injected drugs (26.3 and 26.9%, respectively). Longitudinal factors independently associated with RSS in the multi-level mixed-effects model were recent client violence [adjusted odds ratio (aOR) = 2.17, 95% confidence interval (CI) = 1.09-4.33], having an intimate partner who injected drugs (aOR = 2.18, 95% CI = 0.98-4.85), being injected by others (aOR = 4.95, 95% CI = 2.42-10.10) and obtaining syringes from a street seller (aOR = 1.88, 95% CI = 0.94-3.78) or from a member of their personal network (aOR = 4.43, 95% CI = 2.21-8.90).

Conclusions: Client violence, intimate partner injection drug use, being injected by others and obtaining syringes from personal connections appear to increase parenteral HIV/HCV risk among female sex workers who inject drugs.