The efficacy of different kinds of intravenously applied antiepileptic drugs in the treatment of status epilepticus. How can it be determined?

•When treating status epilepticus, to determine the termination drug is sometimes hard.•Criteria to determine the termination drug should be standardized.•To determine efficacy, use the last drug introduced into the therapy or increase in dose within 24 h before termination

We explored the influence of four different efficacy criteria on the results of observational studies concerning the treatment of status epilepticus (SE) and its subtypes.We compared and contrasted the results of four different efficacy criteria for the effectiveness of phenytoin, valproate, levetiracetam, and lacosamide. Criterion 1 = the last antiepileptic drug (AED) administered before SE termination. Criterion 2 = the last drug introduced into the antiepileptic therapy within 72 h before the cessation of SE and without changes in dosage or number of the co-medication. Criterion 3 = the last drug introduced into the antiepileptic therapy or increased in dose within 24 h before termination of the SE without changes in the co-medication. Criterion 4 = the last drug introduced into the antiepileptic therapy within 72 h before the cessation of SE even allowing changes in the co-medication. We used two-tailed χ2-tests with the Yates adjustment for small samples to evaluate statistical differences between efficacy rates of different AEDs in the entire group and in subgroups of SE according to the second level of subdivisions in axis 1 and according to axis 2 of the new ILAE classification. A total of 145 treatment episodes in 124 patients (47 male, 77 female) were evaluated. There were 23 significant differences in efficacy according to the different criteria. Only criteria 1 and 3 led to significant results in our analysis. When incorporating theoretical considerations and the results of this study, criterion 3 seems to be the most appropriate measure for the evaluation of efficacy of an AED in the treatment of SE, because it seems to be more reasonable than criterion 1.