Injection Behaviors and Use of Syringe Service Programs over Time among People Who Inject Drugs in Baltimore, Maryland.

Introduction: People who inject drugs (PWID) are at increased risk for infectious disease transmission, including hepatitis C and HIV. Understanding trends in injection risk behaviors and syringe service program (SSP) use over time can help improve infectious disease prevention and other harm reduction services. Methods: Using National HIV Behavioral Surveillance System data from Baltimore, Maryland, we examined changes in receptive sharing of (1) syringes, (2) injection equipment, (3) syringes to divide drugs; and (4) receipt of syringes from SSPs among PWID from 2009 to 2018 (n = 518 in 2009, n = 638 in 2012, n = 586 in 2015, and n = 575 in 2018) using unadjusted and adjusted logistic models calculated across time for the total sample. Results: The conditional probability of receptive sharing of syringes and receipt of syringes from SSPs remained relatively stable, while receptive sharing of injection equipment and receptive sharing of syringes to divide drugs dropped substantially after 2009. White race and daily injection frequency were positively associated with sharing syringes and injection equipment and negatively associated with SSP use over time. In 2015, there was a notable shift such that women were twice as likely as men to receive syringes from SSPs and less likely than men to report the use of shared syringes or equipment. Conclusion: Findings indicate overall steady or decreasing trends in injection risk and steady trends in SSP usage over time, with some notable improvements among women and indications of shifting drug market patterns. Injection-related risk behaviors remain high among White PWID and may require targeted outreach and interventions.