Driver licensing rates and motor vehicle crash risk among adolescents with attention deficit hyperactivity disorder

background: Several small studies suggesting teens with ADHD are at heightened crash risk were conducted among more severely-affected adolescents and have significant methodological limitations. We still know little about when teens with ADHD get licensed and whether they are at increased crash risk.

methods: We utilized electronic health records (EHR) to identify 15,854 NJ residents born 1987-1995 who were patients of CHOP’s NJ primary care practices within 4 years of driving-eligible age. Records were individually linked to NJ’s licensing and crash databases through June 2012. Subjects were classified as having ADHD if their EHR indicated an ICD-9-CM code beginning with ‘314’ either at a specific clinical encounter at CHOP or on the list of known chronic conditions. Licensing rates and crash risk were compared for 2,055 teens with and 13,799 teens without ADHD.

results: Adolescents with ADHD were less likely to be licensed by their 19^th birthday (75% vs. 84%, p<0.001). Among those licensed, males with ADHD had a higher crash risk by 1 year (23% vs 19%, RR=1.26 [1.09-1.45]) and 3 years (52% vs. 41%, RR=1.48 [1.29, 1.71]) post-licensure. Females with and without ADHD had similar risks within 1 year of licensure (19% vs 18%, RR=1.07 [0.81-1.39]), but females with ADHD were at increased risk by 3 years post-licensure (49% vs 40%, RR=1.42 [1.10, 1.83]).

conclusions: Teens with ADHD are less likely to become licensed and may be at higher crash risk once licensed. Additional research is needed to understand the specific mechanisms by which ADHD influences crash risk.