Health outcomes associated with illicit prescription opioid injection: A systematic review

Prescription opioid injection is a growing concern among people who use illicit drugs. Little is known about the potential health-related harms of injecting prescription opioids. Therefore, the authors undertook a systematic review to identify health outcomes associated with injecting prescription opioids. PubMed, Ovid MEDLINE®, EMBASE, Journals@Ovid, CINAHL, PsycInfo, Web of Science® Core Collection, CAB Direct, and ERIC databases were searched to identify English articles published between January 1990 and February 2015 that matched the inclusion criteria. Potentially relevant articles were those examining a clinical health outcome among people who use illicit drugs, in which a sub-group injects prescription opioids. The International Classification of Diseases (ICD-10) was used to clinically classify health outcomes. In total, 31 studies that met the inclusion criteria were identified and summarized. A modified version of the Downs and Black checklist was used to assess individual study quality and identify sources of bias. Findings supported associations between prescription opioid injection and hepatitis C infection, substance dependence and other mental health indicators, and lower general health. Associations with human immunodeficiency virus, overdose, and cutaneous infection were less consistent and varied according to prescription opioid type(s). Several potential sources of bias were identified as well as a need for more longitudinal research and more rigorous confounding adjustment. The current findings highlight a need to consider the growing popularity of prescription opioid injection in efforts to reduce drug-related harm among people who inject drugs.