PROGNOSTIC INDEX FOR RECURRENCE OF SEIZURES AFTER REMISSION OF EPILEPSY

Objectives-To develop and test a prognostic index for the recurrence o f seizures after a minimum remission of seizures of two years in peopl e with a history of epilepsy. Design-Information from a large prospect ive randomised study of withdrawal of antiepileptic drugs was used to identify clinical and treatment factors of prognostic importance in de termining the recurrence of seizures. A split sample approach was used to test the internal validity of predictions made on the basis of ide ntified prognostic factors. Setting-Centres in six European countries. Main outcome measures-Comparison of predicted and observed rates of r ecurrence of seizure. Subjects-1013 patients randomised to the Medical Research Council study for antiepileptic drug withdrawal. Results-The Cox proportional hazards model identified several factors that increa sed the risk of seizures recurring. These included being 16 years or o lder; taking more than one antiepileptic drug; experiencing seizures a fter starting antiepileptic drug treatment; a history of primary or se condarily generalised tonic-clonic seizures; a history of myoclonic se izures; and having an abnormal electroencephalogram. The risks of seiz ures recurring decreased with increasing time without seizures. The mo del allowed estimation of the risk of seizures recurring in the next o ne and two years under the policies of continued antiepileptic drug tr eatment and slow withdrawal of drugs. Split sample validation suggeste d that the model was well calibrated. Conclusion-The model is currentl y the best available aid for counselling the many patients in the comm unity with epilepsy currently in remission who seek advice about the r isks of seizures recurring if they stop antiepileptic drug treatment. The model requires validation in a broad population of patients, and s uch studies are in progress.