Data from: Clinical EEG slowing correlates with delirium severity and predicts poor clinical outcomes

Objective To determine which findings on routine clinical EEGs correlate
with delirium severity across various presentations, and to determine
whether EEG findings independently predict important clinical outcomes.
Methods We prospectively studied a cohort of non-intubated inpatients
undergoing EEG for evaluation of altered mental status. Patients were
assessed for delirium within one hour of EEG using the 3-Minute Diagnostic
Interview for Confusion Assessment Method (3D-CAM) and 3D-CAM severity
score (3D-CAM-S). EEGs were interpreted clinically by neurophysiologists,
and reports were reviewed to identify features such as theta or delta
slowing and triphasic waves. Generalized linear models were used to
quantify associations between EEG findings, delirium, and clinical
outcomes, including length of stay, Glasgow Outcome Scale scores, and
mortality. Results We evaluated 200 patients (median age 60 years, IQR
48.5-72); 121 (60.5%) met delirium criteria. The EEG finding most strongly
associated with delirium presence was a composite of generalized theta or
delta slowing (OR 10.3, 95% CI 5.3-20.1). The prevalence of slowing
correlated not only with overall delirium severity (R2 = 0.907), but also
with the severity of each feature assessed by CAM-based delirium
algorithms. Slowing was common in delirium even with normal arousal. EEG
slowing was associated with longer hospitalizations, worse functional
outcomes, and increased mortality, even after adjusting for delirium
presence or severity. Conclusions Generalized slowing on routine clinical
EEG strongly correlates with delirium and may be a valuable biomarker for
delirium severity. Additionally, generalized EEG slowing should trigger
elevated concern for the prognosis of patients with altered mental status.