Epilepsy: Calculating Risks of Driving Post-Seizure

This article originally appeared on HCPLive.com.

Legal restrictions on how long patients who’ve had a seizure must wait before resuming driving a motor vehicle vary widely by state in the U.S.

According to data in an interactive table compiled by the Epilepsy Foundation, some states have no restrictions. In others, Wyoming for instance, there is a 3-month wait. In New Jersey the wait is 6 months, while in New York it is a year. In Florida, patients not under a physician’s supervision must be seizure-free for 2 years before taking the wheel again.

Writing in Neurology Laura Bonnett, PhD, reports that guidelines also vary widely abroad. In the UK and in Australia, she wrote, guidelines set 6 months to 12 months as the “no-driving”period.

“Perhaps the most important question is how do we decide an acceptable level of risk,“ she wrote, “ In the United Kingdom, it is thought to be approximately equal to the risk of an accident involving a newly qualified driver.” But according to Australian data, the average risk ratio for males under the age of 25 years old is more than double the acceptable average risk ratio,” she said. Bonnett’s earlier work, published in the British Medical Journal in 2010, was the basis for those rules. But a newer study by J.W. Brown and colleagues looked at month-by-month changes in recurrence risk, she noted.

In an attempt to use those data with her own to quantify the risk of a seizure recurring, Bonnett looked at 1,386 patients and used survival analysis to prospectively calculate that risk.

Then she looked at how many patients actually had another seizure while driving.

“For a risk of seizure recurrence to fall to 2.5% per month, or a monthly risk of 1.04 per thousand and an accident risk rations of 2.6, non-driving periods of 8 months are required for patients who had an unprovoked first-ever seizure,” she wrote. For patients whose first-ever seizure was provoked, the time period for abstaining from driving should be 5 months, she wrote.” After six months, the risk of a recurrence droved to one per 1,000 patients.

She favors using those guidelines to replace the contradictory standards of the various jurisdictions.

“Our data provide a quantitative approach to decisions regarding a return to driving in patients with first-ever provoked of unprovoked seizure,” she concluded.

In the US, according to the Epilepsy Foundation, so far the matter has been left up to the states—or to physicians in states which set no restrictions. On its site the foundation suggests that patients with epilepsy use the data to help them decide where to live.