Minor increase in risk of road traffic accidents after prescriptions of antidepressants: A study of population registry data in Norway

Objectives: Experimental studies have shown that both depression and the use of antidepressants may impair the ability to drive a motor vehicle. Population-based studies have been inconclusive. Differences in results have been shown for cyclic, sedating antidepressants and newer, nonsedating antidepressants. The objective of the present study was to examine whether the use of antidepressants by drivers increased the risk of being involved in traffic accidents. Method: From April 2004 to September 2006, information on prescriptions, road accidents, and emigrations/deaths was obtained from 3 Norwegian population-based registries. Data on people between the ages 18-69 (N = 3.1 million) were linked. Exposure consisted of receiving prescriptions for any antidepressants. Standardized incidence ratios (SIRs) were calculated by comparing the incidence of accidents during time exposed with the incidence over the time not exposed. Sedating antidepressants (tricyclic antidepressants, mianserin, and mirtazapine) were studied together as one group, and newer, nonsedating antidepressants (selective serotonin reuptake inhibitors, moclobemide, venlafaxine, and reboxetine) as another. Results: During the study period, 20,494 road accidents with personal injuries occurred, including 204 and 884 in which the driver was exposed to sedating antidepressants or newer, nonsedating antidepressants, respectively. The traffic accident risk increased slightly for drivers who had received prescriptions for sedating antidepressants (SIR = 1.4, 95% Cl = 1.2 to 1.6) or nonsedating antidepressants (SIR = 1.6, 95% CI = 1.5 to 1.7). The SIR estimates were similar for mate and female drivers and slightly higher for young drivers (18-34 years of age) using older sedative antidepressants. SIR estimates did not change substantially for different time periods after dispensing of the prescription, for concomitant use of other impairing drugs, or for new users. Conclusion: There was a slightly increased risk of being involved in a traffic accident after having received a prescription for any antidepressants. In the present study, it was not possible to determine whether this increase was due to the antidepressant, the effect of the depression, or characteristics of the patients being prescribed these drugs.