Researchers report the accuracy of a novel delirium screening tool for neurocritically ill patients, the Fluctuating Mental Status Evaluation (FMSE). Their prospective validation study included 139 neurocritically ill stroke patients (mean age, 63.9 years; median NIH Stroke Scale score 11). For the research, trained clinicians conducted paired FMSE assessments and expert raters conducted daily Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition-based delirium assessments. Of 717 noncomatose days of paired assessments, experts determined that 373 (52%) were days with delirium, with 53% of participants delirious on at least one or more days. The FMSE was highly accurate, with an area under the curve (AUC) of 0.85. On a per-assessment basis, FMSE scores ≥1 had 86% sensitivity and 74% specificity, while scores ≥2 had 70% specificity and 88% specificity. The accuracy of the test was high for patients with aphasia and those with decreased arousal and for predicting functional outcomes at discharge (AUC, 0.86) and 3 months (AUC, 0.85). “FMSE scores greater than or equal to 1 indicate “possible” delirium and should be used when prioritizing sensitivity, whereas scores greater than or equal to 2 indicate “probable” delirium and should be used when prioritizing specificity,” the study authors report.