Unlicensed drivers and car crash injury

Previous studies have indicated that unlicensed drivers are more likely to engage in risky driving behaviors, and are more likely than licensed drivers to be at fault and more seriously injured when involved in a crash. However, the prevalence of unlicensed drivers in the general driving population has not been measured, and the risk of an unlicensed driver being involved in an injury crash has not been quantified. We examined the association between unlicensed driving and car crash injury using data from a population-based case control study.

The study population was the drivers of all cars on public roads in the Auckland region. Cases were 571 vehicles involved in a crash resulting in any occupant being hospitalised or killed, from the study base, during the recruitment period. Controls were 588 vehicles selected from the driving population using a random cluster sampling method. The drivers of all vehicles completed a structured interview covering multiple potentially crash-related factors.

Driving unlicensed was reported by 12% of case and 1% of control drivers. Unlicensed drivers were at significantly higher risk of car crash injury than those holding a valid licence (odds ratio 11.1, 95% confidence interval 4.2 to 29.7) after adjustment for age and sex. After further adjustment for education level, ethnicity, driving exposure, time of day, sleepiness score, year of vehicle manufacture, passenger carriage, seatbelt use, blood alcohol concentration, and travelling speed at time of crash, the increased risk was still present but no longer significant (OR 3.9, 95% CI 0.7-22.4).

Unlicensed drivers are a high risk group for car crash injury after taking other crash-related risk factors into account. Strategies to reduce unlicensed driving may therefore facilitate reductions in road crashes, although further work is needed in this area.