Characteristics of U.S. emergency department visits for altered mental status, 2016-2022

Altered mental status (AMS) is a frequent reason to visit the emergency department (ED), and it carries a broad differential diagnosis. There is a lack of nationally representative data on the clinical characteristics and diagnostic patterns of ED visits for AMS.

We performed a cross-sectional analysis of adult ED visits for AMS using data from the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2016 to 2022. Visits for AMS were identified using the primary reason for visit variable recorded in the survey instrument. We evaluated demographics, clinical features, and discharge diagnoses (identified using ICD-10-CM codes). We applied survey visit weights to obtain nationally representative estimates and report 95 % confidence intervals (CI).

Visits for AMS accounted for 3.1 % (95 % CI, 2.9-3.4) of all ED visits during the study period representing approximately 4.5 million annual visits. Among all ED visits for AMS, mean age was 50 years (SD: 21.0), 43.6 % were women, and 60.3 % arrived via ambulance. Diagnostic testing in the ED was common, with head CT performed in 29.2 % (95 % CI, 26.4 %-32.1 %) of visits, and specialist consultation sought in 22.3 % (95 % CI, 18.9 %-26.1 %). The most common ED discharge diagnoses were nonspecific symptoms or signs (e.g., syncope, nausea and vomiting, unspecified abdominal pain) in 27.1 % (95 % CI, 24.3 %-30.2 %) of visits, psychiatric diagnoses in 26.0 % (95 % CI, 23.5 %-28.7 %) of visits, injuries in 13 % (95 % CI, 11.4 %-14.8 %) of visits, alcohol or drug-related disorders in 9.3 % (95 % CI, 7.6 %-11.4 %) of visits, and neurological diseases in 4.9 % (95 % CI, 3.8 %-6.4 %) of visits. Patients were discharged to home from the ED in 38 % (95 % CI, 34.4 %-41.7 %) of visits.

In a contemporary, nationally representative sample of visits for AMS to U.S. EDs, the most common discharge diagnoses were nonspecific symptoms or signs (syndromic), suggesting potential opportunities to improve diagnostic accuracy for these patients.