The Role of Marital Status in the Association between Benzodiazepines, Psychotropics and Injurious Road Traffic Crashes: A Register-Based Nationwide Study of Senior Drivers in Sweden

BACKGROUND Among senior drivers, benzodiazepines (BZDs) have a documented effect on the risk of road traffic crashes (RTCs). It remains unclear however if BZDs play the same role when considering marital status. Therefore, we aimed to investigate the role of marital status in the association between BZD use and injurious RTCs among senior drivers. METHODS Matched case-control study based on five national Swedish registers (n = 154 225). Cases comprised the first non-alcohol-related injurious RTC sustained by drivers aged 50-80 years from July 2005 to December 2009 and controls included registered residents with a valid license who did not crash during that period. Four controls were matched to each case by sex, age and place of residence. Conditional logistic regression analysis for injurious RTC was performed with adjustment for occupation and number of medications. The main exposure was dispensation of BZDs, alone or in combination with other psychotropic medications, 1-30 days prior to the crash date stratified by marital status. RESULTS BZD use, alone or in combination with other psychotropic medications, increased the risk of being involved in an RTC (BZD only: adjusted OR: 1.26, 95% CI: 1.17-1.36; BZDs and other psychotropics: adjusted OR: 1.25, 95% CI: 1.12-1.41). Compared to married drivers, those divorced (1.48, 1.43-1.53) and widowed (1.54; 1.45-1.63) had higher adjusted ORs. Marital status modified the association between BZDs and RTCs, particularly among younger male drivers. CONCLUSIONS Both BZDs and marital status independently affect the risk for senior drivers to be involved in an RTC. However, marital status plays a role in the association between BZD use and RTCs and this may have implications for targeting risk populations for RTCs among senior drivers.