How accurately do adult patients report their absence seizures?

We depend upon self‐reporting to determine seizure frequency for epilepsy management decisions, but people often misreport their seizures. Here, we determined misreporting rates in adults with absence seizures, undergoing inpatient video‐EEG telemetry (VET) or outpatient ambulatory electroencephalography (aEEG). Under‐reporting rates were based on VET data, where behavior could be assessed, whilst over‐reporting was assessed using both VET and aEEG. Forty‐two patients (31 female and 11 males, median age 28.5 years) and 759 reported absence seizures were included in this study. Overall, only 24% of the 759 reported seizures had an associated EEG correlate, indicating a high over‐reporting rate, which occurred in 57% of patients. Age, sex, time of epilepsy, VET versus aEEG, epilepsy syndrome, or medication were not significant predictors of over‐reporting. In the VET group in which we could assess both over‐ and under‐reporting (22 patients), only 2 patients correctly reported their seizures, and patients were predominantly over‐reporters or under‐reporters, not both. Only 26% of 423 absence seizures were reported. Use of zonisamide or valproate was associated with under‐reporting, possibly through an impact on attention. These findings indicate that self‐reported absence seizures are a poor measure to use for treatment decisions due to both over‐ and under‐reporting.