“From a clinical perspective, it is important to consider the combined effects of illness, medication use, and associated changes in lifestyle so that our results can assist patients and clinicians in making informed decisions about treatment and driving safety,” Zheng Chang, Ph.D., of the Karolinska Institutet and colleagues wrote.
For the study, Chang and colleagues used data contained in the Truven Health Analytics MarketScan Commercial Claims and Encounters database to identify people aged 18 and older who had received an ADHD diagnosis or ADHD medication between January 2005 and the end of December 2014. Patients were tracked from first inpatient or outpatient diagnosis or filled prescription until first disenrollment (zero days of medical or drug coverage in a month) or December 31, 2014, whichever came first. The number of emergency department visits for motor vehicle crashes for these patients was compared with those of non-ADHD controls matched by sex, age at first enrollment, length of enrollment, and more.
The study cohort consisted of 2,319,450 patients diagnosed with ADHD (1,121,053 men and 1,198,397 women). During the follow-up, 1,946,198 patients (83.9%) received at least one prescription for an ADHD medication. A total of 11,224 patients (0.5%) had at least one emergency department visit for a motor vehicle crash. Patients with ADHD had a significantly higher risk of a motor vehicle crash than their matched controls (odds ratio [OR]=1.49 for men and OR=1.44 for women). Untreated patients with ADHD had the highest risk of a motor vehicle crash compared with medicated patients with ADHD and controls.
Chang and colleagues also compared the risk of motor vehicle crashes in individual patients during medicated and unmedicated months. The analyses showed that men and women with ADHD were 38% and 42%, respectively, less likely to have motor vehicle crashes during medicated months relative to unmedicated months. Moreover, ADHD medication use was associated with a 34% lower risk of accidents two years later in male patients with ADHD and a 27% lower risk in female patients with ADHD.
“[T]his study is the first to date to demonstrate a long-term association between receiving ADHD medication and decreased MVCs [motor vehicle crashes]. If this result indeed reflects a protective effect, it is possible that sustained ADHD medication use might lead to lower risk of comorbid problems … or contribute to long-term improvements in life functioning,” the authors wrote.
In a related editorial, Vishal Madaan, M.D., and Daniel Cox, Ph.D., of the University of Virginia Health System noted that the findings reaffirm support for the use of ADHD medications for drivers with ADHD who respond to the medications. However, they emphasized that some medications may be less effective later in the day when the medications may have worn off.
“Individualizing and optimizing ADHD pharmacotherapy, while being mindful of adverse effects and the potential for abuse, is the most prudent way forward,” the researchers concluded.
For related information, see the Psychiatric News article “Better Ways to Treat Child ADHD, New Thinking for Adults Needed.”