Circumstances surrounding the first injection experience and their association with future syringe sharing behaviors in young urban injection drug users.

Young injection drug users are at heightened risk for acquisition of blood-borne infections because of their high rates of unsafe injection behaviors, yet there has been little research examining the circumstances surrounding injection drug users' first injection experience ('hit'). We examined the relationship between factors associated with young drug users' first hit and their future syringe sharing behaviors among 420 new initiates to injection drug use (less than 5 years), aged 15-30 years old in urban Baltimore, Maryland. Contingency table analysis and logistic regression were used to determine the association between circumstances surrounding the first hit and recent receptive syringe sharing. Participants were primarily male (58.8%), White (71.2%), and were a median age of 24 years (interquartile range [IQR]: 21-27 years). Adjusting for race, gender, and homelessness, the following variables were independently associated with recent receptive syringe sharing: age at first hit (adjusted odds ratio [AOR] = 0.92 per year increase; 95% confidence interval [CI]: 0.87-0.98), self-injection at initiation (AOR = 0.55; 95% CI: 0.32-0.97) and using a syringe that had previously been used by someone else at first hit (AOR = 2.81; 95% CI: 1.70-4.64). These data suggest that injection-related risk behaviors may be established as early as the onset of injection initiation, supporting the need to educate non-injectors of the harms associated with unsafe injection practices.