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Prognosis

The seizure recurrence rate was high, especially shortly after seizure

ACP J Club. 1991 Mar-April;114:54. doi:10.7326/ACPJC-1991-114-2-054


Source Citation

Hart YM, Sander JW, Johnson AL, Shorvon SD. National General Practice Study of Epilepsy: recurrence after a first seizure. Lancet. 1990;336:1271-4. (See also Sander JW, Hart YM, Johnson AL, Shorvon SD. National General Practice Study of Epilepsy: newly diagnosed epileptic seizures in a general population. Lancet. 1990;336:1267-71.) [PubMed ID: 1978114]


Abstract

Objective

To investigate the risk for recurrence of seizures after a first epileptic attack.

Design

Inception cohort.

Setting

Community-based study.

Patients

Only patients having definite epileptic seizures were included. Of the 564 included, 71% were 16 years of age or older, and 51% were men or boys. The cohort was assembled at the time of the first seizure and followed to seizure recurrence, death, or last available follow-up date known to be seizure free. 460 patients (82%) were followed for 2 to 4 years; 12% died and 7% were lost to follow-up.

Assessment of prognostic factors

Cause of initial seizure, type of seizure, number of seizures, age, and treatment.

Main outcome measure

Seizure recurrence.

Main results

A recurrence occurred within 12 months of the first seizure for 67% of patients (95% CI 63% to 71%), and within 36 months for 78% (CI 74% to 81%). The greatest risk for recurrence occurred in the early months after the first seizure. Factors affecting the risk for recurrence were cause — the highest risk being for seizures associated with a neurologic deficit presumed present at birth (100% by 12 mo); age — the highest risk being for patients < 16 years old (83% by 36 mo, CI 77% to 89%) or older than the age of 59 years (83% by 36 mo, CI 76% to 90%); and type of first seizure — the highest risk being for patients with simple partial or complex partial seizures (94% by 36 mo, CI 90% to 99%). Only 15% of patients were treated after the first seizure. Recurrence rates were lower in treated patients than in untreated patients: 50% recurrence by 12 months (CI 40% to 61%) compared with 70% (CI 66% to 74%), and 57% recurrence by 36 months (CI 46% to 68%) compared with 81% (CI 77% to 85%), respectively.

Conclusions

The recurrence rate for seizure was high (78% at 36 months), with the greatest risk for recurrence in the early months after the first seizure. Factors affecting the risk for recurrence were cause, age, type of seizure, and treatment.

Sources of funding: Brain Research Trust; the National Fund for Crippling Diseases; the British Epilepsy Research Foundation; the National Society for Epilepsy.

Address for article reprint: Dr. Y.M. Hart, Atkinson Marley's Hospital, Department of Neurology, Copse Hill, Wimbledon, London SW19 ONE UK.


Commentary

The clinical approach to patients with a single seizure remains uncertain mainly because of conflicting data on the risk for recurrence. The study by Hart and colleagues is an important contribution because of its superior study design. Because it was population based, the problem of selection bias was avoided. Also, patients were identified at an early, uniform point in their disease. Clinicians should be cautious, however, in drawing conclusions on the effect of cause on seizure recurrence because the extent of diagnostic investigation was not the same for all patients. A minor problem with the estimate of risk in this study was that 15% of patients were treated with an anticonvulsant, which would change the prognosis for the treated patients. The effect, however, would tend to lower the risk for recurrence falsely. Therefore, the true risk for recurrence may actually be even higher than this study suggests. Because the risk for recurrence is high, clinicians should consider treating patients after a first seizure, especially patients with neurologic deficits that are presumed to be present at birth, those younger than 16 years or older than 59 years, and those with simple partial or complex partial seizures.

Barbara Scherokman, MD
U.S. Naval HospitalPortsmouth, Virginia, USA