Deep vein thromboses in users of opioid drugs: incidence, prevalence, and risk factors.

BACKGROUND Users of illicit opioids are at increased risk of hospital admission for deep vein thromboses (DVTs); however, the community prevalence, risk factors, and complications of DVTs in this group are poorly understood. AIM This study aimed to describe the prevalence of previous DVT for users of opioids in primary care; provide age- and sex-adjusted annual incidence rates of DVT; and explore factors associated with DVT, concordance with subsequent treatment, and complications. DESIGN A retrospective analysis of DVT prevalence and incidence, and analysis of risk factors for DVT using Poisson regression of incidence rates. METHOD A review of 734 patients in treatment for opioid addiction, who were registered to a single, specialised primary care practice in Middlesbrough, England. RESULTS The prevalence of previous DVT in users of opioids was 13.9% (95% confidence interval [CI] = 11.5 to 16.6) with an annual incidence rate of 3.2% (95% CI = 2.6 to 3.7). The incidence rate increased with age and for female users; an exploration of risk factors suggests that rising age, female sex, sex-worker status, and intravenous delivery all independently increase the risk of DVT. Concordance with treatment appeared reasonable and, compared with DVT in groups of people who do not use drugs, there was no evidence of increased risk of pulmonary embolism. Participants with previous DVT reported lower health and wellbeing scores. CONCLUSION Primary care providers should be aware of the considerably increased risk of DVT and its sequelae in users of intravenous drugs. Evidence for effective primary care prevention and the effective management of DVT complications is lacking; until this emerges, vigilance on the part of clinicians may help to minimise harm.