Recurrence risk of seizure after incident episode

January 01, 0001

Recurrence risk of seizure after incident episode

Determining seizure risk and when patient are safe to return to driving are challenges that face physicians. These British researchers examined how long after a first unprovoked seizure a driver needed to be seizure-free before the risk of recurrence drops below 20%, which is a threshold used to allow a return to driving. They performed a randomized controlled trial, the Multicentre study of early Epilepsy and Single Seizures (MESS). The subset of people used for this analysis 16 years old or older with a single unprovoked seizure.

The researchers found: "At six months after the index seizure the risk of recurrence in the next 12 months for those who start antiepileptic drugs was significantly below 20% (unadjusted risk 14%, 95% confidence interval 10% to 18%). For patients who did not start treatment the risk estimate was less than 20% but the upper limit of the confidence interval was greater than 20% (18%, 13% to 23%). Multivariable analyses identified subgroups with a significantly greater than 20% risk of seizure recurrence in the 12 months after a six month seizure-free period, such as those with a remote symptomatic seizure with abnormal electroencephalogram results."

The researchers concluded: "After a single unprovoked seizure this reanalysis of MESS provides estimates of seizure recurrence risks that will inform policy and guidance about regaining an ordinary driving licence. Further guidance is needed as to how such data should be utilized. In particular, whether a population approach should be taken with a focus on the unadjusted results or whether attempts should be made to individualise risk. Guidance is also required as to whether the focus should be on risk estimates only or on the confidence interval as well. If the focus is on the estimate only our unadjusted estimates suggest that treated and untreated patients are eligible to drive after being seizure-free for six months. If the focus is also on confidence intervals, direction is needed as to whether a conservative or liberal approach should be taken."

While it appears overall the risk of recurrence is relatively low whether on medications or not for many subpopulations, the policy devil is in the details

For the full abstract, click here.

BMJ 341:c6477, 7 December 2010
© 2010 BMJ Publishing Group Ltd.
Risk of recurrence after a first seizure and implications for driving: further analysis of the Multicentre study of early Epilepsy and Single Seizures. L J Bonnett, C Tudur-Smith, P R Williamson, A G Marson. Correspondence to A G Marson: [email protected]

Category: N. Neurological. Keywords: seizure, epilepsy, recurrence, driving, MESS, randomized controlled trial, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 17 December 2010 2010

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