Objectives: To evaluate the effect of intensive care unit continuous EEG (cEEG) monitoring on inpatient mortality, hospital charges, and length of stay.Methods: A retrospective cross-sectional study was conducted using the Nationwide Inpatient Sample, a dataset representing 20% of inpatient discharges in nonfederal US hospitals. Adult discharge records reporting mechanical ventilation and EEG (routine EEG or cEEG) were included. cEEG was compared with routine EEG alone in association with the primary outcome of in-hospital mortality and secondary outcomes of total hospital charges and length of stay. Demographics, hospital characteristics, and medical comorbidity were used for multivariate adjustments of the primary and secondary outcomes.Results: A total of 40,945 patient discharges in the weighted sample met inclusion criteria, of which 5,949 had reported cEEG. Mechanically ventilated patients receiving cEEG were younger than routine EEG patients (56 vs 61 years; p , 0.001). There was no difference in the 2 groups in income or medical comorbidities. cEEG was significantly associated with lower in-hospital mortality in both univariate (odds ratio 5 0.54, 95% confidence interval 0.45-0.64; p , 0.001) and multivariate (odds ratio 5 0.63, 95% confidence interval 0.51-0.76; p , 0.001) analyses. There was no significant difference in costs or length of stay for patients who received cEEG relative to those receiving only routine EEG. Sensitivity analysis showed that adjusting for diagnosis-related groups (DRGs) for any neurologic diagnoses, DRGs for neurologic procedures, and specific DRGs for epilepsy/ convulsions did not substantially alter the association of cEEG with reduced inpatient mortality.Conclusions: cEEG is favorably associated with inpatient survival in mechanically ventilated patients, without adding significant charges to the hospital stay. Continuous EEG (cEEG) is increasingly utilized in critically ill patients with abnormal neurologic function. cEEG can detect convulsive and nonconvulsive seizures, brain ischemia, and other disturbances as they occur, prompting adjustment of anticonvulsants 1,2 or interventions to reverse focal ischemia.3,4 For seizures, only cEEG can provide this diagnostic information; for detection of focal ischemia, cEEG may be more sensitive than imaging 5 and gives uninterrupted bedside appraisal. Encephalopathic patients may benefit from cEEG 6 even in the absence of known acute brain injury. 7The evidence for cEEG has focused on rates of seizure detection in specific patient populations, 8 and the significance of particular EEG patterns.9-11 Meaningful improvement in patient outcomes has yet to be demonstrated. 12,13The literature regarding costs, charges, or cost-effectiveness of cEEG is more limited. A singlecenter study showed that cEEG was responsible for only 1% of total hospital charges for From the Departments of Neurology (J.P.N.) and Health Services (L.N.),