Emergency department (ED) volumes have increased 30% since 2005 to over 150 million visits in 2019 [1,2], resulting in worsening capacity challenges despite any increases in hospital capacity [3]. Increased ED crowding has resulted in decreased patient satisfaction, increased patient mortality and excess financial burden [[4], [5], [6]]. ED crowding, coupled with boarding, strains ED capacity, and creates a barrier to patients' timely access to care. In response, ED administrators have created and utilized care spaces not initially designed for patient care such as hallways stretchers or waiting room chairs to facilitate patient flow and provide timely access to care.

Assigning patients for care in hallway beds should only occur under the most extreme or disastrous circumstances based on the clinical appropriateness of the patient's presentation and resources available for their care [7,8]. However, hospitals lack consistent policies guiding hallway placement decisions and less is known about triage and treatment space assignment to hallways based on the contemporary operations literature. Studies have demonstrated that Black patients are more likely to be physically restrained or flagged for behavioral issues resulting in less testing, treatment and increase departure without complete evaluation [9,10]. Operational stress can further exacerbate biases and decrease quality of care. Prior work has highlighted the impact of socio-economic factors on the odds of hallway placement in the ED [7], but results were limited because confounding ED operational factors such as boarding (known to increase ED crowding which is strongly associated with hallway utilization ([8,11]) were not adjusted for. Furthermore, hallway bed usage has been associated with LWBS, elopement or discharge AMA [12]. These are indicators of impeded access to ED and hospital care and potentially worse clinical outcomes. We aimed to explore social risk factors associated with hallway bed utilization and association with downstream care outcomes.