Reliability of seizure diaries in adult epileptic patients.

Daily diaries are used widely in neurologic research and clinical practice to assess alterations in seizure frequency among patients with epilepsy. However, no formal tests of the reliability of this data collection method have been performed. We investigated the reliability of seizure recall in adult patients participating in a longitudinal study of stress, mood and seizure frequency. Patients maintained daily diaries for 10-36 weeks. The reliability study entailed completion of a single additional diary on the evening of a randomly selected day with reference to the preceding day. This design produced two diaries, completed 1 day apart, for the same 24-hour period. Measuring reliability with the Pearson correlation coefficient, overall reliability of seizure recall was 0.95 and was not markedly influenced by the subjects' sociodemographic characteristics, neurological or psychological status. In sum, the assumption in the literature that the daily diary is a reliable method for securing data on seizure counts appears warranted.