To determine whether inpatient electroencephalographic (EEG) features are associated with functional independence, cognitive impairment, and mortality post-hospitalization. 

Delirium is a neuropsychiatric disturbance commonly found in hospitalized patients, particularly older adults, associated with lower cognitive scores and increased mortality. While clinical assessments such as the Confusion Assessment Method exist, EEG findings have been shown to predict delirium. Considering the association between delirium and long-term outcomes, EEGs may be useful for prognosis.

We conducted a two-site prospective cohort study of hospitalized adults expected to stay at least one night. Patients underwent delirium assessment and EEG recording. At 3-months post-hospitalization, participants were contacted for follow-up, including the telephone Montreal Cognitive Assessment (t-MoCA), Telephone Interview for Cognitive Status (TICS), and Basic and Instrumental Activities of Daily Living (bADL/iADL) survey. Cognitive impairment was measured using cutoffs for TICS and t-MoCA. EEG features were analyzed for correlations with functional independence, cognitive impairment, and mortality.

We enrolled 334 adults; 155 (46.4%) completed 3-month follow-up, and 25 (7.5%) died by 3 months. Greater mean theta power and lower delta and beta variability were associated with worse functional independence (bADL/iADL; p < 0.05). Lower mean beta power and greater theta variability were associated with worse instrumental function (p < 0.05). Greater mean theta power and variability and lower mean beta power and variability were associated with cognitive impairment (p < 0.05). Greater mean theta power and alpha and delta variability were associated with mortality (p < 0.05). After adjustment for age and dementia status, greater theta power and variability remained associated with cognitive impairment, and greater delta variability remained associated with mortality (p < 0.05).

Inpatient EEG features were associated with functional independence, cognitive impairment, and mortality. EEGs may serve as objective prognostic tools, highlighting their potential role in identifying high-risk patients and guiding interventions for acutely ill individuals.