Currently, 1% to 2% of people who go to the emergency department (ED) present with complaints of syncope -- transient, self-limited loss of consciousness [1] with an inability to maintain postural tone that is followed by spontaneous recovery. It's a number that has been rising steadily in recent years. Of greater concern is syncope recurrence, which is seen in as many as 20% of cases. The patient can get hurt if an episode happens while they're engaging in everyday activities, such as going up and down stairs or swimming. And if syncope occurs while they're driving, an accident could injure others as well.
Researchers in Canada performed a retrospective study to examine whether patients visiting the ED with first-episode syncope have a higher subsequent motor vehicle crash (MVC) risk. The study compared 9223 individuals visiting the ED after first-episode syncope with a control group of 34,366 average ED patients (median age: 54 years).
The most common causes of syncope were vasovagal (68%) and orthostatic (12%). During the year after the index ED visit, a first vehicular accident occurred in 9% of the syncope group and in 10% of the control group — a nonsignificant difference. Also, the subsequent MVC risk was not higher during the first 30 days after the index ED visit in the syncope group, nor among subgroups at higher risk for adverse events after syncope (such as older patients and patients with cardiogenic syncope).
The findings suggest that patients visiting the ED with first-episode syncope have a risk for subsequent crash that is no different than that of the average ED patient, according to the researchers.
Are Restrictions Needed?
The Canadian study concluded that more stringent driving restrictions after syncope may not be warranted. Its results can be explained by the fact that the most common types of syncope were vasovagal and orthostatic, which are known to be more benign.
In the editor's note accompanying the publication, Cary P. Gross, MD, and Mark R. Rosekind, PhD, advise caution when interpreting the results. They point out that because there has not been enough research into the matter, no clear guidance can be given. Indeed, they cite data from prior work that suggest exactly the opposite of the Canadian study's conclusions: that syncope is associated with an increased risk of MVC. In addition, Gross and Rosekind criticize the study's methodology, such as its use of a control group of patients who went to the ED for a condition other than syncope and not taking into consideration other MVC risk factors (such as driving habits).
Clinical Implications
A significant aspect of the Canadian study is the low median age of the patients (54 years).
As I and others have noted, recurrent syncope is common, and its incidence depends on its etiology and the number of previous syncope episodes. In addition, recurrent syncope is a major predictor of death and major adverse cardiovascular events (MACE) if occurring within the first 8 to 12 months after the index event ("vulnerable phase"). Reflex syncope, a more benign condition, is common in younger individuals. But in older people, other types such as cardiac syncope seem to be the main causes of recurrence and poor prognosis.
As we get on in years, being able to get in our own car and drive becomes ever more important to maintaining a sense of independence and freedom. This is just one reason why a reasonable and practical approach should be taken when making decisions about driving restrictions.
Given the risks involved, I think that, while we seek to clarify the cause, we must have driving restrictions for older people with syncope — especially in that "vulnerable phase" of the first few months after the index event.
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