Concurrent Use of Benzodiazepines and Antidepressants and the Risk of Motor Vehicle Accident in Older Drivers: A Nested Case–Control Study

INTRODUCTION Aging of the population results in an increase in senior drivers. Elderly are frequently treated with benzodiazepines and antidepressants. The objective of this study was to determine whether the concurrent use of benzodiazepines and antidepressants is associated with motor vehicle accidents (MVAs) in the elderly. METHODS This was a nested case-control study within a cohort of drivers aged 67-84 years between 1990 and 2000, identified from the Société de l'Assurance Automobile du Québec and the Régie de l'Assurance Maladie du Québec databases. First cases of MVAs during follow-up were matched with up to ten controls from the cohort. Odds ratios (ORs) for the association between MVA and the use of benzodiazepines and antidepressants were estimated using conditional logistic regression. RESULTS The cohort included 373,818 drivers, with 74,503 MVA cases matched with 744,663 controls. The risk of MVA was higher in current users of long-acting benzodiazepines [OR 1.23; 95% confidence interval (CI) 1.16-1.29] than in current users of short-acting benzodiazepines (OR 1.05; 95% CI 1.02-1.08). The risk of MVA was increased in current users of selective serotonin reuptake inhibitors (SSRIs; OR 1.13; 95% CI 1.04-1.22), while it was not in current users of tricyclic antidepressants (TCAs; OR 1.04; 95% CI 0.96-1.14). The highest ORs of MVA were observed in long-acting benzodiazepines users concurrently using SSRIs (OR 1.37; 95% CI 1.07-1.77, P value for interaction = 0.964) or TCAs (OR 1.54; 95% CI 1.21-1.95, P value for interaction = 0.077). CONCLUSION Use of long-acting benzodiazepines is associated with an increased risk of MVA in the elderly, particularly in those concurrently using SSRIs or TCAs.