Secondary Syringe Exchange As a Means of HIV Prevention in Injection Drug Users---King County, Washington, 2013 *

BACKGROUND:  Injection drug use is associated with increased risk of HIV and hepatitis C transmission. Syringe exchange programs prevent disease transmission by providing injection drug users (IDU) with sterile syringes and other injection equipment. Secondary exchange of syringes on behalf of others may increase the number of IDU effectively served by a syringe exchange. 

METHODS:  The Public Health-Seattle & King County (PHSKC) syringe exchange program conducts a biannual client survey for program planning and evaluation. We conducted a 10-minute, interviewer-administered survey of clients at the 3 PHSKC syringe exchange sites in 2013. We assessed the prevalence of secondary exchange (exchange by individual clients for themselves and others) and compared socioeconomic characteristics and drug use behaviors between clients who exchanged only for themselves (sole exchangers) and clients who performed secondary exchanges.    

RESULTS:  Among 475 surveyed syringe exchange clients, 32% performed secondary exchanges. These clients exchanged syringes for a mean of 5 individuals (range 1-100). The mean age (38 years), proportion of male clients (69%), and proportion of white clients (69%) did not differ significantly between secondary and sole exchangers.  Men who have sex with men (MSM) were just as likely as non-MSM men to perform secondary exchanges. Secondary exchangers did not differ significantly from sole exchangers in education, housing status, income, incarceration history, or time since first injection. The two groups were equally likely to report obtaining more than half of their syringes from a syringe exchange or pharmacy (93%). Syringe sharing (23%) was not significantly different between the groups, but sole exchangers reported less sharing of other drug use equipment (42%) than secondary exchangers (52%) (p=0.056). Sole  exchangers were more likely to reuse their own syringes (62%) than secondary exchangers (50%) (p=0.02). Sole exchangers were also more likely to inject heroin as their main drug (73%) than secondary exchangers (62%) (p=0.01) whereas secondary exchangers were more likely to inject methamphetamine as their main drug (22%) than sole exchangers (12%) (p<0.01).

CONCLUSIONS:  Our findings demonstrate that secondary exchange serves a greater number of IDU than primary exchange. The differences in syringe reuse and sharing of other drug use equipment support the promotion of secondary exchange of both syringes and other equipment to further maximize HIV risk reduction.  Further research is needed to better understand the relationships between secondary exchangers and their recipients, the characteristics of the recipients, and the impact of secondary exchange on disease prevention.