Use of psychotropic medication and risk of road traffic crashes: a registry-based case-control study in Denmark, 1996-2018.

Rationale: Use of psychotropics is relatively prevalent amongst motor vehicle drivers because mobility is also important for persons suffering from psychiatric illness. However, medication side effects may increase the likelihood of being involved in traffic crashes.

Objectives: This study aimed to assess the association between the use of four types of medication (antipsychotics, benzodiazepines and z-hypnotics, antidepressants and stimulants of ADHD treatment) and the risk of traffic crashes, in general, and single crashes subsequently.

Method: We conducted a case-control study of data from 130,000 drivers involved in traffic crashes with personal injury and prescription data from all of Denmark during the period 1996-2018.

Results: For antipsychotics, we found odds ratios of 0.86 and 1.29 for traffic crashes and single crashes, respectively; for benzodiazepines and z-hypnotics, 1.29 and 2.49, respectively; for antidepressants, 1.30 and 2.25, respectively; and for stimulants of ADHD treatment, 1.62 and 1.95, respectively. All p values were below 0.001.

Conclusions: Based on our results on twofold increased risks of single crashes and moderately increased risks in persons with ADHD, it might seem tempting to ban psychotropic medication in traffic. Conversely, we accept increased risks of traffic crashes in young drivers and in the physically disabled with special aids and, to some extent, with exposure to alcohol. In the end, it is the authorities who must review the evidence and decide whether to prohibit (some types of) psychotropic medication in traffic. Finally, underlying disease and not the drug may increase the risk of being involved in a traffic crash.