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Prior syncope linked to increased risk for motor vehicle crashes

Being previously hospitalized for syncope was associated with an increased risk for future motor vehicle accidents over a period of 5 years, and physicians should consider prior fainting as one of several factors in determining whether patients are fit to drive, according to data published in JAMA Internal Medicine.

“Syncope is characterized by a sudden loss of consciousness, although with spontaneous and complete recovery, and could have serious consequences for public safety if it occurs in the driver of a motor vehicle,” Anna-Karin Numé, MD, of the department of Cardiology at Copenhagen University Gentofte Hospital, in Denmark, and colleagues wrote. “In addition, about one-third of patients with syncope will experience recurrent events within 3 years, so physicians face a difficult judgement about whether patients with syncope are fit to drive.”

To determine the existence of a link between prior syncope and an increased risk for motor vehicle crashes, the researchers conducted a nationwide cohort study in Denmark from Jan. 1, 2008 to Dec. 31, 2012. Included in the study were 41,039 Danish residents aged 18 years or older, with a first-time diagnosis of syncope from an emergency department or hospital. The median age of the patients was 66 years, 51% were women and 34.8% had cardiovascular disease.

The researchers measured the rate of motor vehicle crashes, both fatal and nonfatal, using multivariate Poisson regression models, with the population of Denmark as a reference.

According to the researchers, 4.4% of the patients with syncope had a motor vehicle accident throughout a median follow-up period of 2 years.  Of the 1,791 crashes, 78.1% led to injury, while 0.3% were fatal. The crude incidence rate of motor vehicle accidents was almost doubled among participants with prior syncope, with 20.6 crashes per 1,000 person-years (95% CI, 19.7-21.6), compared with 12.1 per 1,000 person-years in the general population (95% CI, 12-12.1). After adjusting for age, sex, socioeconomic position and relevant comorbidities and pharmacotherapy, the rate ratio was 1.83 (95% CI, 1.74-1.91). At 5-year follow-up, the risk for a crash following syncope was 8.2% among those aged 18 to 69 years (95% CI, 7.5%-8.8%), compared with 5.1% among the general population (95% CI, 4.7%-5.4%).

“Since the absolute crash risk was relatively small, whether syncope should lead to restrictions on a patient’s ability to drive is a difficult policy question that must balance multiple considerations,” Numé and colleagues wrote. “We urge increased physician awareness about driving recommendations, accurate diagnosis and appropriate treatment for patients with syncope to reduce motor vehicle crashes.”

In a related editorial, Donald A. Redelmeir, MD, FRCPC, MSHSR, and Sheharyar Raza, HBSc, both of the department of medicine at the University of Toronto, in Canada, said the study raises several issues when applied to the United States, which they say has twice the baseline rate of traffic deaths per 100,000 individuals.

“At a minimum, physicians could consider asking patients about driving when eliciting a medical history,” Redelmeir and Raza wrote. “Numé et al provide a timely reminder for clinicians to consider traffic safety when managing a patient with syncope. Doing so will not clarify the diagnosis but might help prevent a life-threatening complication.” – by Jason Laday

Disclosure: Numé reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures. Redelmeir and Raza report no relevant financial disclosures.