How reliable is early treatment response in predicting long-term seizure outcome?
Assessing if an early therapeutic response to an antiepileptic drug (AED) is of prognostic value for long-term outcome is of considerable clinical interest. To that end, we evaluated the likelihood that a patient who becomes seizure-free after 6 months of treatment with a single AED would lose that response at 12 months, or vice versa. In a post hoc analysis, data from five comparative, double-blind, single-drug studies designed to evaluate the efficacy of treatment of patients with partial seizures with oxcarbazepine versus carbamazepine, phenobarbital, phenytoin, and valproate for approximately 1 year were pooled to investigate same-patient seizure outcome at 6 and 12 months. These studies had similar dosing regimens and included a wide range of patients with newly diagnosed and chronic epilepsy. The main finding in the population included in the analysis is that those patients who are seizure-free at 6 months have a 90% chance of being seizure-free at 12 months, whereas those not seizure-free at 6 months have only a 45% chance of being seizure-free at 12 months (chi(2)=118.716, P<0.000001, odds ratio=11.23 with 95% confidence limits 6.8-18.7). In a worst-case assessment, those not seizure-free at 6 months have only an 18% chance of being seizure-free at 12 months (chi(2)=408.105, P<0.000001, odds ratio=41.23 with 95% confidence limits 26.4-65.85). Failure to maintain the response in 10% of patients, including 4% with two or more seizures, was noted with all AEDs studied here and in patients with newly diagnosed as well as chronic epilepsy. Among patients with seizures in Months 1-6, those with newly diagnosed epilepsy became seizure-free more often over time than those with chronic epilepsy. The main conclusion is that response at 6 months is an excellent predictor of response at 12 months.
Schmidt
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Epilepsy Research Group, Berlin, Goethestrasse 5, D-14163 Berlin, Germany. dbschmidt@t-online.de
D000293:Adolescent; D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D016001:Confidence Intervals; D004311:Double-Blind Method; D004827:Epilepsy / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011379:Prognosis; D012640:Seizures / Q000188:drug therapy*; D016037:Single-Blind Method; D016896:Treatment Outcome
D000927:Anticonvulsants