# Prior Concussions and Risk of Disability for Patients After a Motor Vehicle Crash

## TL;DR

Having a prior concussion increases the risk of long-term disability after a motor vehicle crash, according to a large study of Canadian patients.

## Contribution

The study identifies a 15% increased risk of long-term disability following a motor vehicle crash for individuals with a prior concussion.

## Key findings

- Patients with a prior concussion had a 15% higher adjusted risk of long-term disability after a motor vehicle crash.
- The increased risk was consistent across crash severity and patient groups, and was confirmed using artificial intelligence models.
- The risk was independent of other factors and not linked to higher short-term healthcare costs or mortality.

## Abstract

Is a prior concussion associated with an increased risk of long-term disability following a motor vehicle crash?

In this cohort study of 907 984 adult patients, a prior concussion was associated with a 15% increased risk of long-term disability.

This finding suggests the importance of counseling patients about the risks of motor vehicle crashes and previous concussions, as well as the importance of follow-up care to reduce the risk of subsequent disability.

This cohort study of Canadian adults surviving a motor vehicle crash examines the association of prior concussions with risk of long-term disability.

Recovery after a motor vehicle crash can be slow, frustrating, and incomplete with lingering neurocognitive complications.

To examine whether a prior concussion is associated with increased risk of long-term disability after a motor vehicle crash.

This cohort study included adults surviving a motor vehicle crash treated in Ontario, Canada, from April 2003 to March 2023 with analyses to November 2025.

Prior concussion.

Long-term disability defined by official social service records, comparing those with a prior concussion and those with no history of a prior concussion.

A total of 907 984 patients injured in a motor vehicle crash were included (mean [SD] age, 37 [14] years; 472 435 male [52.0%]); 19 851 patients had a prior concussion and 888 133 had no prior concussion. A total of 54 678 patients were subsequently diagnosed with long-term disability over 9 543 505 patient-years of follow-up (mean [SD], 10.5 [5.8] years), equal to an absolute risk of 1 in 17 per decade (5.7 per 1000 patient-years). Patients with a prior concussion had a 15% higher adjusted risk of long-term disability (95% CI, 9%-21%; P < .001) compared with those with no prior concussion. The increased risk of long-term disability was independent of other measured risk factors, applied to diverse patient groups, and included those involved as passengers or pedestrians. The increased risk extended across a spectrum of crash severity, was accentuated for single-vehicle events, replicated in analyses with artificial intelligence models adjusting for confounding, and remained distinct from the risks of death, readmission, or short-term health care costs.

This population-based cohort study suggests a significant increased risk of long-term disability after a motor vehicle crash, particular among patients with a prior concussion. More efforts at concussion prevention and traffic safety counseling may be justified for patients.