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 Researchers focused on people who experience syncope – a sudden loss
of consciousness unrelated to a head injury – and found that
affected individuals had almost twice the risk of motor vehicle
accidents compared with the general population.
“This risk was small in absolute terms, yet raises important
questions about policies toward driving,” said lead study author Dr.
Anna-Karin Nume of Copenhagen University Gentofte Hospital in
Denmark.
“This is one particular instance of drivers who develop medical
conditions that could affect their driving ability, and there are
tradeoffs between restrictions on driving and the ability of the
patients to work, shop, etc.,” Nume added by email.
Roughly one in three people will experience syncope at least once in
their lifetime, and about one-third of patients who have one episode
will experience another one within three years of the first event,
Nume and colleagues report in JAMA Internal Medicine.
Syncope may be caused by a variety of circumstances including
dehydration, overheating, emotional stress, pooling of blood in the
legs, or exhaustion, as well as by medical conditions that affect
the nervous system or the heart.
To assess how syncope influenced the odds of car crashes,
researchers examined data on almost 4.3 million Danish adults from
2008 through 2012, including about 41,000 individuals with a syncope
diagnosis.
About one-third of the patients with syncope had cardiovascular
disease, and half of them were at least 66 years old.
Researchers followed half of the syncope patients for at least two
years and found 1,791 of them had a motor vehicle crash during the
study.
Roughly four in five crashes resulted in injuries; just six of the
accidents were fatal.
After adjusting for age, sex, socioeconomic status, other medical
conditions and drug regimens, people with syncope were 83 percent
more likely to have a crash, the study found. The odds of crashes
were higher for men with syncope than for women.
The five-year crash risk for people with a history of syncope was
8.2 percent among the population aged 18 to 69 years old, compared
with 5.1 percent in the general population.
One shortcoming of the study is its focus on observational data,
which made it impossible for researchers to say whether syncope
directly caused crashes or what types of circumstances contributed
to episodes of fainting or blackouts, the authors note. Researchers
also lacked crash data on alcohol or drug use, seat belts or road
conditions.
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Even so, the findings provide a reminder to clinicians to consider
traffic safety when managing patients with syncope, Dr. Donald
Redelmeier of the University of Toronto and Sunnybrook Health
Sciences Center wrote in an accompanying editorial.
While road rules for people with syncope vary, eight U.S. states
require doctors to notify vehicle licensing authorities of episodes
involving a loss of consciousness, Redelmeier said by email.
“Each case will be different, depending on the specific medical
diagnosis,” Redelmeier added. “A uniform policy of license
suspension, therefore, would be overly draconian and
counterproductive.”
Other things like young or old age, drowsiness, speeding, drinking
or texting contribute to crashes and are also bigger causes of
crashes than syncope, said Carol Chen-Scarabelli, a researcher at
the Birmingham VA Medical Center in Alabama who wasn’t involved in
the study.
“Despite the concern of syncope-related driving accidents, there are
many other conditions or factors which contribute to motor vehicle
accidents to a greater degree,” Chen-Scarabelli said by email.
That’s because with syncope, drivers often have several seconds or
minutes of symptoms like dizziness or heart palpitations before
losing consciousness, said Dr. Dan Sorajja, a researcher at Mayo
Clinic in Arizona who wasn’t involved in the study.
“This duration usually gives people enough time to pull over and
avoid an accident,” Sorajja said by email. “There are a subset of
people who have no warning prior to losing consciousness, and these
persons may be at increased risk of accidents.”
SOURCE: http://bit.ly/1QH7O0r JAMA Internal Medicine, online
February 29, 2016.
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