Initial treatment response predicts long-term seizure control
MedWire News: The long-term treatment outcomes of about two-thirds of patients with epilepsy can be predicted from their response to the first two drug regimens tried, study results show.
The researchers found a very low chance for patients becoming seizure free if they failed to respond to the first two drugs tried.
"Nevertheless, all hope for a good prognosis is not lost even after further drug trials," say Patrick Kwan (Royal Melbourne Hospital, Australia) and colleagues.
In all, 49.5% of the 1098 patients in the study became seizure free on the first drug regimen tried (monotherapy), and 13.3% became so on the second regimen (monotherapy or combination). An additional 3.7% of patients responded to the third regimen, and the response rates fell to 0.2-1.0% for patients trying fourth to seventh regimens. No patients responded to eighth or ninth regimens.
Patients with symptomatic (41% of the cohort) or cryptogenic (36%) epilepsy were particularly unlikely to respond to treatment having failed two regimens.
The patients were drawn from those who were referred to and began treatment at a single epilepsy unit in Glasgow, UK. This approach captured a wide range of epilepsy patients, rather than only refractory cases who had already failed to respond to one or more drugs, note Kwan et al. The patients were aged a median of 32 years, ranging from 9 to 93 years.
Most patients had a predictable response to treatment, with 37% achieving freedom from seizures that started within 6 months of treatment initiation and lasted through follow up (median 7.5 years), and 25% persistently failing to respond.
But 22% of patients achieved sustained freedom from seizures after a delay of 6 months or more, and 16% had a fluctuating response to treatment, with seizure-free periods lasting at least 1 year interspersed with periods of relapse.
"Recognizing the latter two outcome patterns is important because they suggest that drug response can be a dynamic process," the researchers write in Neurology.
In an editorial accompanying the paper, Patricia Penovich (University of Minnesota School of Medicine, St Paul, USA) and Michael Gruenthal (Albany Medical Center, New York, USA) say: "The take-home message remains the simple observation that failure of two drug regimens used maximally and with good adherence is strongly suggestive of a patient with a refractory course.
"Although these and other authors describe occasional seizure freedom with additional drug regimens, the number of patients who benefit remains small. We interpret this as compelling evidence that patients who do not respond to two regimens should be offered additional evaluations to verify the diagnosis of epilepsy and identify potential opportunities for surgical treatment."
By Eleanor McDermid