Etiologies of altered level of consciousness in the emergency room.

Altered levels of consciousness (ALCs) is a challenging issue; however, data describing its etiology and frequency are lacking. This study aimed to clarify and classify the etiologies of ALCs in the emergency room (ER) and to evaluate their destinations and the form of discharge. This retrospective study included patients with an ALC who visited the ER of a university hospital between January 2018 and December 2020. The cause and classification of the ALCs were carefully determined by a consortium of board-certified faculty members in emergency medicine, internal medicine, and neurology. The reference point for determining the etiology of ALC was discharge from the ER. In total, 2028 patients with ALCs were investigated. More than half (1037, 51.1%) visited the ER between 9:00 and 18:00. The most common etiology was systemic infection (581, 28.6%), followed by metabolic causes (455, 22.4%), and stroke (271, 13.4%). The two leading etiologies were extracranial and had a majority of the cases (1036, 51.5%). The overall mortality rate was 17.2%. This study provides fundamental information on ALC in the ER. Although intracranial etiologies have been foregrounded, this study demonstrated that extracranial etiologies are the main cause of ALC in the ER.