F185. Comparison of ambulatory and inpatient 24 h EEG: A value analysis

Abstract

Introduction Although admission into an epilepsy monitoring unit (EMU) has been the standard modality in the evaluation of epilepsy and paroxysmal spells, ambulatory electroencephalography (AEEG) is also widely used. At a national level, the average charge for 24 h video-EEG monitoring (CPT 95951) is 75% higher than AEEG (CPT 95953). While there are advantages of EMU monitoring, the relative value of these modalities in terms of quality of results per cost is not known. Methods This is a retrospective cohort study comparing the diagnostic yield between 24 h EMU and AEEG studies from 1/1/16 through 9/27/17. All the patients had at least one prior routine EEG. 67 adult individuals underwent a 24 h EMU evaluation and 43 underwent AEEG. Chart review was performed to evaluate if either modality changed treatment, established a new diagnosis of epilepsy, or diagnosed non-epileptic spells. Results The discovery rate of epileptiform discharges of EMU patients was 38.8% vs 28.4% on routine EEG, and was 50% for AEEG patients vs 18.2% on routine EEG (chi-squared p-value = 0.06). There was no significant difference in seizure detection (p-value = 0.5). Non-epileptic events were diagnosed at comparable rates (15% EMU, 13.6% AEEG). EMU results led to initiation of a new drug in 14.9%, while AEEG led to initiation of a new drug in 21.4%; however, these differences were not significant. Treatment changed in 22.4% of EMU and 34.1% of AEEG patients (p-value = 0.10). Conclusion These data suggest that 24 h AEEG is non-inferior to 24 h EMU evaluation. The lower EEG fee and absence of other hospital costs suggests AEEG is of higher value than EMU for certain non-surgical indications.