Serious transport accidents in adults with attention-deficit/hyperactivity disorder and the effect of medication: a population-based study.
OBJECTIVE
Studies have shown that attention-deficit/hyperactivity disorder (ADHD) is associated with transport accidents, but the magnitude of the association remains unclear. Most important, it is also unclear whether ADHD medication reduces this risk.


OBJECTIVE
To estimate the association between ADHD and the risk of serious transport accidents and to explore the extent to which ADHD medication influences this risk among patients with ADHD.


METHODS
In total, 17,408 patients with a diagnosis of ADHD were observed from January 1, 2006, through December 31, 2009, for serious transport accidents documented in Swedish national registers. The association between ADHD and accidents was estimated with Cox proportional hazards regression. To study the effect of ADHD medication, we used stratified Cox regression to compare the risk of accidents during the medication period with the risk during the nonmedication period within the same patients.


METHODS
Serious transport accident, identified as an emergency hospital visit or death due to transport accident.


RESULTS
Compared with individuals without ADHD, male patients with ADHD (adjusted hazard ratio, 1.47; 95% CI, 1.32-1.63) and female patients with ADHD (1.45; 1.24-1.71) had an increased risk of serious transport accidents. In male patients with ADHD, medication was associated with a 58% risk reduction (hazard ratio, 0.42; 95% CI, 0.23-0.75), but there was no statistically significant association in female patients. Estimates of the population-attributable fractions suggested that 41% to 49% of the accidents in male patients with ADHD could have been avoided if they had been receiving treatment during the entire follow-up.


CONCLUSIONS
Attention-deficit/hyperactivity disorder is associated with an increased risk of serious transport accidents, and this risk seems to be possibly reduced by ADHD medication, at least among male patients. This should lead to increased awareness among clinicians and patients of the association between serious transport accidents and ADHD medication.
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
Zheng
Z
Chang
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
Paul
P
Lichtenstein
Department of Psychological and Brain Sciences, Indiana University, Bloomington.
Brian M
BM
D'Onofrio
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
Arvid
A
Sjölander
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
Henrik
H
Larsson
D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012042:Registries; D012306:Risk; D012737:Sex Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult