The Association between Substance Use Disorders and Long-Term Outcome of Stroke: Results from a Population-Based Study of Stroke among 450,229 Urban Citizens

Introduction: Little is known regarding long-term stroke outcomes in patients with substance use disorder (SUD). Based on anecdotal data, some individuals use illicit drugs, particularly opioids, in an attempt to reduce stroke mortality, disability, or recurrence. This study is aimed to assess the effect of SUD on stroke outcomes.

Methods: Patients were recruited from the Mashhad Stroke Incidence Study, a population-based study of stroke in Iran. For a period of 1 year, all patients with first-ever stroke (FES) were recruited and then followed up for the next 5 years. Disability and functional dependency were defined using modified Rankin Scale (>2) and Barthel Index (<60), respectively. We compared the cumulative rates of mortality in follow-up points using the log-rank test. We used multivariable logistic, Cox regression and competing risk models to assess adjusted hazard ratio (aHR) with 95% confidence interval (CI) of stroke disability, functional dependency, mortality, and recurrence among those with a history of SUD.

Results: 595 FES patients (mean age of 64.6 ± 14.8 years) were recruited in this study. Eighty-one (13.6%) were current substance users, including opium (n = 68), naswar (n = 5, 6.1%), hashish (n = 1), heroin (n = 1), and (n = 7) others. The frequency of vascular risk factors was similar between the SUD and non-SUD groups, except for a higher rate of cigarette smoking in the SUD group (p < 0.001). After adjusting for various sociodemographic variables, vascular risk factors, and the severity of stroke at admission, SUD increased the 3-month (aHR: 1.60, CI: 1.01-2.49), 1-year (aHR: 1.73, CI: 1.20-2.65), and 5-year (aHR: 1.72, CI: 1.23-2.35) poststroke mortality risk. We did not observe a significant change in the risk of stroke recurrence, disability, and functional dependency in those with a history of SUD.

Conclusion: SUD increased the hazard ratio of stroke mortality with no effect on the disability rate. The public should be advised about the potential harm of substance abuse.