Altered mental status: evaluation and etiology in the ED.

The purpose of this study was to determine the etiologies responsible for altered mental status (AMS) in an emergency department (ED) population, to gauge the diagnostic (DX) value of the various features of the clinical evaluation, and to examine patient outcomes. Prospective identification of patients with AMS followed by a retrospective review of the medical record was performed in a university hospital E among ED patients with AMS. Three hundred seventeen patients (5% of the ED patient volume) were identified with a mean age of 49 years (57% men). Descriptions of the AMS included 24% unresponsive, 46% lethargic/difficult to arouse, 12% agitated, and 18% unusual behavior. The most common discharge diagnoses accounting for AMS were neurologic (28%) and toxicologic (21%) followed by trauma (14%), psychiatric (14%), infectious (10%), endocrine/metabolic (5%), pulmonary (3%), oncologic (3%), cardiovascular (1%), gastrointestinal (1%), and renal (1%). The specific features of the clinical evaluation of greatest DX value followed by rates of positive DX finding included history of present event (51%), past medical history (43%), and physical examination (41%); features of little DX value included radiographs (16%), 12-lead electrocardiogram (7%), and various laboratory studies (chemistry panel [5%], complete blood count [1%], coagulation panel [0], urinalysis [11%]). Sixty-four percent of the patients were admitted with a mean hospital stay of 7.6 days and 9% deaths. Common causes of AMS included neurologic, toxicologic, traumatic, and psychiatric syndromes. The patient history and physical examination were most useful in DX terms; ancillary investigations were less often DX. This group represented a minority of the ED population yet rates of ED resource use, hospital admission, and death were high.