TOPLINE:

A history of concussion was associated with a 49% higher risk for motor vehicle crashes in adults than more benign injuries such as ankle sprains, with the risk rising to 124% after three concussions, a new population-based study showed.

METHODOLOGY:

• Researchers conducted a population-based retrospective cohort study in Ontario using health records from 2002 to 2022 and included more than 425,000 adults diagnosed with a concussion (57% male; 52% aged 18-39 years; 88% living in urban areas) and more than 2.6 million individuals diagnosed with ankle sprains to act as the control group (55% male; 42.5% aged 18-39 years; 90% living in urban areas).
• The primary outcome was subsequent emergency visits for motor vehicle crashes compared between the two groups. Crashes were defined as incidents requiring acute treatment.
• Secondary outcomes included the assessment of the potential association between past concussions and risk for subsequent motor vehicle crashes, adjusting for demographic, clinical, and socioeconomic confounders. Patients were followed for a median of 10 years.

TAKEAWAY:

• More than 200,000 patients experienced motor vehicle crashes during follow-up. Patients with a concussion had an absolute risk of 10.6 per 1000 annually compared with 6.2 per 1000 for those with a sprained ankle (relative risk [RR], 1.61; P < .001).
• After adjusting for demographic and clinical variables, patients with a concussion had a 49% higher risk for a crash (adjusted RR, 1.49; P < .001). The risk was sixfold higher in the first month after injury, accounting for more than 5000 crashes during this period.
• Risk for motor vehicle crashes increased with multiple concussions: 73% higher after one, 114% after two, and 124% after three concussions (P < .001 for all).
• Other risk factors for motor vehicle crashes included younger age, male sex, residence located in a rural area, a lower socioeconomic status, late-night driving, and alcohol misuse. However, women with a concussion had a higher absolute risk for crashes (9.9 per 1000) than men without a concussion (6.7 per 1000; P < .001).

IN PRACTICE:

“The risk of a motor vehicle crash after a concussion suggests current mitigating efforts are insufficient; however, driving cessation may be unreasonable since the risk also extends to patients as pedestrians,” the investigators of the study wrote.

“Further strategies might include temporarily reducing traffic exposure by avoiding high-speed trips during adverse late-night hours,” they added.

SOURCE:

The study was led by Donald A. Redelmeier, MD, Sunnybrook Research Institute, Toronto, Ontario, Canada. It was published online on November 05 in BMJ Open.

LIMITATIONS:

Factors that predisposed patients to concussions may have also predisposed them to a traffic crash, preventing the establishment of causal inferences. Additionally, the study was limited by a lack of data on concussion severity, prior brain injuries during remote years, interval treatments, and traffic exposure. An at-fault analysis was also absent. Furthermore, diagnostic codes may have been inexact, and unmeasured confounding factors may have predisposed individuals to both concussions and motor vehicle crashes.

DISCLOSURES:

The study was supported by Institute for Clinical Evaluative Sciences, which was funded by a grant from the Ontario Ministry of Health and the Ministry of Long-Term Care. The investigators reported having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.