Under the skin: The relationship between subcutaneous injection and skin infections among people who inject drugs

OBJECTIVES People who inject drugs (PWID) are at increased risk for numerous negative health outcomes. Subcutaneous injections (aka skin popping) can result in greater risk of skin and soft tissue infections (SSTIs), but less is known about PWID who choose this route of administration. This study compares subcutaneous injectors to intravenous injectors, characterizes those who inject subcutaneously, and examines whether subcutaneous injection is associated with SSTIs in the past year. METHODS A cohort of hospitalized PWID (n = 252) were interviewed regarding injection-related behaviors, history of SSTI, and knowledge of subcutaneous injection risk. We examined differences between those who do and do not inject subcutaneously and used a negative binomial regression model to estimate adjusted odds associating subcutaneous injection and SSTI. RESULTS Participants averaged 38 years, with 58.3% male, 59.5% White, 20.6% Black, and 15.9% Latinx. PWID who performed subcutaneous injection were not demographically different from other PWID; however, the mean rate of past year SSTIs was higher for persons injecting subcutaneously than for those who did not (1.98 vs 0.96, P