Declining trends in the rates of assisted injecting: a prospective cohort study

Jeanette Somlak Pedersen, Huiru Dong, Will Small, Evan Wood, Paul Nguyen, Thomas Kerr, Kanna Hayashi

Assisted injecting has been associated with increased risk of blood-borne infections, overdose, and other harms among people who inject drugs (PWID), particularly women. Given the changing availability of relevant harm reduction interventions in Vancouver, Canada, in recent years, we conducted a gender-based analysis to examine changes in rates and correlates of assisted injecting over time among active PWID. Using data from a prospective cohort of PWID in Vancouver, we employed gender-stratified multivariable generalized estimating equations to examine trends in assisted injecting and identify the correlates during two periods: June 2006-November 2009 and December 2009-May 2014. Among 1119 participants, 376 (33.6 %) were females. Rates of assisted injecting declined between 2006 and 2014 among males (21.9 to 13.8 %) and females (37.0 to 25.6 %). In multivariable analyses, calendar year of interview also remained independently and negatively associated with assisted injecting among males (adjusted odds ratio [AOR] 0.95, 95 % confidence interval [CI] 0.92-0.99) and females (AOR 0.93, 95 % CI 0.89-0.97). Syringe borrowing remained independently associated with assisted injecting throughout the study period among females (AOR 1.53, 95 % CI 1.10-2.11 during 2006-2009; AOR 2.15, 95 % CI 1.24-3.74 during 2009-2014) and during 2009-2014 among males (AOR 1.88, 95 % CI 1.02-3.48). Our findings demonstrate assisted injecting has significantly decreased for both males and females over the past decade. Nevertheless, rates of assisted injecting remain high, especially among women, and are associated with high-risk behavior, indicating a need to provide safer assisted injecting services to these vulnerable sub-populations of PWID.