Motor Vehicle Accident Risk after Methadone Use: A Population-Based Study

Abstract

Background: Opioid dependence, a major global public health concern, can be alleviated through methadone maintenance treatment (MMT). However, MMT possibly increases motor vehicle accident risk. The aim of this study was to determine motor vehicle accident risk in MMT users. Methods: We performed preliminary estimation of motor vehicle accident incidence rates in Taiwan. In this population-based retrospective cohort study with frequency-matched controls, adult opiate users receiving MMT and not receiving MMT (control) were identified at a 1:2 ratio by linking data from several nationwide administrative registry databases. All individuals were followed for motor vehicle accident events. Data were adjusted for potential covariates and assessed using Kaplan–Meier and Cox proportional hazard model analyses. Findings: From 2009 to 2016, the crude incidence rate of motor vehicle accidents was the lowest in the general adult population, followed by that in adult opiate users, and it was the highest in adults receiving MMT. Among opiate users, motor vehicle accident incidence rates were significantly higher in those receiving MMT than in those not receiving MMT (adjusted hazard ratio [aHR] 2.75, 95% CI 1.87–4.04; p<0.001). Kaplan–Meier curves of the incidence of motor vehicle accidents differed significantly between groups (log-rank test p<0.001), with a significant decline during the first 90 days of follow-up. Rural area residents had a higher motor vehicle accident risk than did urban area residents (aHR 1.56, 95% CI 1.05–2.32; p=0.029). Interpretation: Drivers receiving MMT have an increased motor vehicle accident risk, particularly during the first 90 days of MMT. These findings should be considered for motor vehicle accident prevention in opiate users receiving MMT. Funding Taiwan Food and Drug Administration. Funding Statement: This study was supported by 2 grants from the Taiwan Food and Drug Administration (TFDA) (MOHW106-FDA-D-114-000671 and MOHW107-FDA-D-114-000636). Declaration of Interests: Authors have no potential conflicts of interest to disclose. Ethics Approval Statement: The study was approved by the Institutional Review Boards (TSMH IRB No.: 17-010-B1 and 18-049-B); the need for written informed consent was waived because we used deidentified information from the databases.