Not in the vein: 'missed hits', subcutaneous and intramuscular injections and associated harms among people who inject psychoactive drugs in Bristol, United Kingdom

Background: The extent of intentional or accidental subcutaneous and intramuscular injections and the factors associated with these have rarely been studied among people who inject drugs, yet these may play an important role in the acquisition bacterial infections. This study describes the extent of these, and in particular the factors and harms associated with accidental subcutaneous and intramuscular injections (i.e. ‘missed hits’). Methods: People who inject drugs were recruited using respondent driven sampling. Weighted data was examined using bivariate analyses and logistic regression. Results: The participants mean age was 33 years (31% aged under 30-years), 28% were women, and the mean time since first injection was 12 years (N = 329). During the preceding three months, 97% had injected heroin, 71% crack-cocaine, and 16% amphetamines; 36% injected daily. Overall, 99% (325) reported that they aimed to inject intravenously; only three aimed to inject subcutaneously and one intramuscularly. Of those that aimed to inject intravenously, 56% (181) reported ever missing a vein (for 51 this occurred more than four times month on average). Factors associated with ‘missed hits’ suggested that these were the consequence of poor vascular access, injection technique and/or hygiene. ‘Missed hits’ were twice as common among those reporting sores/open wounds, abscesses, or redness, swelling and tenderness at injection sites. Conclusion: Intentional subcutaneous and intramuscular injections are rare in this sample. ‘Missed hits’ are common and appear to be associated with poor injection practice. Interventions are required to reduce risk through improving injecting practice and hygiene