Syncope and Motor Vehicle Crash Risk
Is there excess risk of motor vehicle crashes among patients with syncope compared with the general population?
Through individual-level linkage of nationwide administrative registers, all Danish residents 18 years or older were identified. Among 4,265,301 Danish residents, the authors identified 41,039 individuals with a first-time diagnosis of syncope from emergency department or hospital.
The 41,039 patients with syncope had a median age of 66 years, and 35% had cardiovascular disease. Through a median follow-up of 2.0 years, 1,791 patients with syncope had a motor vehicle crash. The crude incidence rate of motor vehicle crashes was almost doubled among patients with syncope (20.6 per 1,000 person-years) compared with the general population (12.1 per 1,000 person-years). After adjustment for age, sex, socioeconomic position, and relevant comorbidities and pharmacotherapy, individuals with syncope were about 83% more likely to have a subsequent motor vehicle crash. The 5-year crash risk following syncope was 8.2% compared with 5.1% in the general population. The excess risk of motor vehicle crashes persisted throughout the follow-up period.
Prior hospitalization for syncope was associated with increased risk of motor vehicle crashes throughout the follow-up period.
According to an expert consensus, syncope has been thought to place individuals at increased risk of a subsequent motor vehicle accident. While prohibitions against driving following loss of consciousness vary among jurisdictions, in most states in the United States it is 6 months. The excess risk of motor vehicle crashes in this unique study persisted throughout the mean follow-up period of 2 years, suggesting that patients remain at elevated risk despite having satisfied the 6-month prohibition. Unfortunately, the specific causes of syncope were not reported. Future studies should examine whether vasovagal syncope carries a lower risk of motor vehicle accident than unexplained or cardiac syncope.
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