Injection-site vein loss and soft tissue abscesses associated with black tar heroin injection: A cross-sectional study of two distinct populations in USA

Background Injection-site vein loss and skin abscesses impose significant morbidity on people who inject drugs (PWID). The two common forms of street heroin available in the USA include black tar and powder heroin. Little research has investigated these different forms of heroin and their potential implications for health outcomes. Methods A multiple-choice survey was administered to a sample of 145 participants seeking services at reduction facilities in both Sacramento, CA and greater Boston, MA, USA. Multivariate regression models for reporting one or more abscesses in one year, injection-site veins lost in six months, and soft tissue injection. Results Participants in Sacramento exclusively used black tar (99%), while those in Boston used powder heroin (96%). Those who used black tar heroin lost more injection-site veins (β = 2.34, 95% CI: 0.66–4.03) and were more likely to report abscesses (AOR = 7.68, 95% CI: 3.01–19.60). Soft tissue injection was also associated with abscesses (AOR = 4.68, 95% CI: 1.84–11.93). Consistent venous access (AOR: 0.088, 95% CI: 0.011–0.74) and losing more injection sites (AOR: 1.22, 95% CI: 1.03–1.45) were associated with soft tissue injection. Conclusion Use of black tar heroin is associated with more frequent abscesses and more extensive vein loss. Poor venous access predisposes people who inject drugs to soft tissue injection, which may constitute a causal pathway between black tar heroin injection and abscess formation. The mechanisms by which black tar heroin contributes to vein loss and abscess formation must be further elucidated in order to develop actionable interventions for maintaining vein health and decreasing the abscess burden. Potential interventions include increased access to clean injection equipment and education, supervised injection facilities, opioid substitution therapy, and supply chain interventions targeting cutting agents.