Objective: Seizure control is often assessed using patient-reported seizure frequencies. Despite its subjectivity, self-reporting remains essential for guiding anti-seizure medication (ASM) decisions and ongoing patient investigations. Additionally, clinical trials frequently rely on self-reported seizure rates for participant selection and outcome measures. This study aims to compare patient-reported seizure frequencies with electrographic frequencies captured via ambulatory video EEG (avEEG). Methods: Data from intake forms and seizure diaries were collected from patients undergoing home-based avEEG in Australia (April 2020 to April 2022). Intake forms included monthly seizure frequency estimates. Only avEEG-confirmed epilepsy cases were analyzed. Univariate and multivariate analyses compared seizure frequencies reported via EEG, diaries, and surveys. Results: Of 3,407 reports, 853 identified epilepsy cases, with 234 studies analyzed after excluding outliers. Diary-reported frequencies correlated with EEG frequency (p<0.00001), but survey-reported frequencies did not (p>0.05). Surveys significantly overestimated seizure frequency (median = 3.98 seizures/month, p<0.0001), while diaries showed substantially smaller differences (median = 0.01 seizures/month, p<0.0001). Carer presence was associated with higher diary-reported frequencies (p=0.047). Age negatively correlated with survey frequency estimation error (p=0.016). Multivariate analysis identified age and carer status as significant predictors of residuals. Conclusions: Most patients overestimate their seizure frequency, influencing therapeutic decisions and raising concerns about the reliability of self-reported data in clinical trials. Significance: An over-reporting, over-prescribing cascade may affect epilepsy treatment and highlights the issue of clinical drug trials relying on self-reported seizure rates.

MC and EN have a financial interest in Seer Medical Holdings Ltd. MC has a financial interest in Epiminder Pty Ltd. The other authors have no conflicts to declare.

No specific funding was received for this study.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethics approval for this study was obtained from the St. Vincent's Hospital Melbourne Human Research Ethics Committee

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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Data used in this study are available upon reasonable request to the corresponding author.