Update on the Risk of Motor Vehicle Collision or Driving Impairment with Dementia: A Collaborative International Systematic Review and Meta-Analysis.

Guidelines that physicians use to assess fitness to drive for dementia are limited in their currency, applicability, and rigor of development. Therefore, we performed a systematic review to determine the risk of motor vehicle collisions (MVCs) or driving impairment caused by dementia, in order to update international guidelines on driving with dementia. Seven literature databases (MEDLINE, CINAHL, Embase, etc.) were searched for all research studies published after 2004 containing participants with mild, moderate, or severe dementia. From the retrieved 12,860 search results, we included nine studies in this analysis, involving 378 participants with dementia and 416 healthy controls. Two studies reported on self-/informant-reported MVC risk, one revealing a four-fold increase in MVCs per 1,000 miles driven per week in 3 years prior, and the other showing no statistically significant increase over the same time span. We found medium to large effects of dementia on driving abilities in six of the seven recent studies that examined driving impairment. We also found that persons with dementia were much more likely to fail a road test than healthy controls (RR: 10.77, 95% CI: 3.00-38.62, z = 3.65, p < 0.001), with no significant heterogeneity (χ2  = 1.50, p = 0.68, I2  = 0%) in a pooled analysis of four studies. Although the limited data regarding MVCs are equivocal, even mild stages of dementia place patients at a substantially higher risk of failing a performance-based road test and of demonstrating impaired driving abilities on the road.