Drug presence in driving deaths in Maryland: Comparing trends and prevalence in medical examiner and FARS data.

Accurate and reliable information on drug use by road users is essential to inform safety policy development but the reliability of national data has been questioned. There are two primary repositories of drug test information from fatal motor vehicle crashes in Maryland: (1) the Fatality Analysis Reporting System (FARS), which is a national crash database managed by the US Department of Transportation, and (2) the Maryland Medical Examiner (ME). In this study, we compared drug test information for people killed in crashes in Maryland between the FARS system and ME from 2006 - 2018. As ME records are the primary source for the FARS data from Maryland, these two data sets should be closely correlated. We used probabilistic linkage to match FARS and ME cases and compared matched cases by individual drug group. Matching was achieved on 83 % of cases (N = 4803 matched pairs). ME data consistently indicated higher overall incidence and trends in the presence of depressants, narcotics, and stimulants in crash deaths. Sensitivity analysis using both strict and relaxed matching criteria did not change this result. Road safety policy and prevention efforts for crashes involving drugs and alcohol require an accurate understanding of both long-term trends and year-to-year changes in drug prevalence. These findings demonstrate the potential value of using ME data as source of drug test information for crash deaths in the United States.