Study Raises Questions About Safety of Drivers with Fainting, Blackout History

A new Danish study indicates that drivers who have a history of fainting, blacking out or losing consciousness are much more likely to be involved in an automobile accident, suggesting that this should be considered when assessing an individuals fitness to drive.

In the latest issue of the medical journal JAMA Internal Medicine researchers compared the risk of accidents between the general population and drivers diagnosed with syncope, a condition which causes temporary loss of consciousness. The findings suggest that a syncope diagnosis was associated with an 83% increased risk of being involved in a motor vehicle crash, usually resulting in injuries.

The study was presented by lead author Dr. Anna-Karin Nume, of the Copenhagen University Gentofte Hospital in Denmark, with the intent of examining whether individuals with a syncope diagnosis were at an increased risk of motor vehicle crashes when compared to the general population. The researchers also looked at whether a syncope diagnosis should be considered when assessing whether someone is fit to drive.

Syncope is considered as a transient, self-limited loss of consciousness resulting in the inability to maintain postural tone. The condition is commonly caused by irregular blood pressures and heart conditions causing a sudden lack of blood supply to the brain. It is known to cause individuals to experience unexpected fainting spells or blackouts for short period of times.

The majority of syncope patients begin experiencing symptoms of dizziness or heart palpitations several seconds or minutes prior to a blackout episode, giving them time to pull over and avoid an accident. However certain subsets of patients have reported no prior warnings before complete loss of consciousness.

The study evaluated about 4.2 million Danes over the age of 18 from January 2008 to December 31, 2012. Of the 4.2 million subjects evaluated, 41,039 individuals were diagnosed with a first-time diagnosis of syncope from an emergency department of hospital. The study aimed to compare crash rates between the general population and individuals with syncope diagnosis.

After two years, the results indicated roughly 4.4% or 1,791 patients with a syncope diagnosis had a motor vehicle crash, in which almost 80% resulted in serious injuries; twice the accident rate of the general population. After five years, the number of syncope patients in accidents had risen to 8.2%, compared to only 5.1% of the general population.

Nume’s study concluded that individuals with prior hospitalization for syncope are associated with increased vehicle crash risks throughout the duration of the study at both the two year and five year follow-up periods, suggesting that further considerations for syncope patients should be evaluated during driving fitness assessments.

Currently in the United States, only eight states require doctors to notify the Motor Vehicle Administration or any vehicle licensing authority of patients involved in sporadic loss of consciousness episodes.