Febrile convulsions followed by nonfebrile convulsions: analysis based on a maximum likelihood method and discriminant function.

Two hundred sixty-two nontreated patients with febrile convulsions only and 107 with later nonfebrile convulsions were analyzed based on a maximum likelihood method and discriminant function. The formula for discrimination is as follows: y = 2.9193 x (basic EEG abnormality at the first examination) + 2.2134 x (more than 20 minutes in duration of convulsion) + 1.7358 (fever under 38.4 degrees C before convulsion) + 1.7005 x (specific EEG abnormality at the first examination) + 1.6703 x (more than 5 recurrences) + 1.5610 x (over 4 years of age at the last convulsion) + 1.4921 x (exogenous causes) + 0.3741 x (family histroy of febrile convulsions among second or third relatives)--3.0397. If an item is positive, coefficient x 1 is to be used, and if it is negative, coefficient x 0 is to be applied. When one classifies patients with y greater than 0 as the FCC group, and those with y less than 0 as the FC group, misclassification may be theoretically expected in 18.9% of cases (accuracy in 81.1%).