Operational and demographic predictors of leaving without being seen in a high-volume tertiary emergency department: a five-year case–control study

Background Patients who leave the emergency department (ED) without being seen (LWBS) represent a critical quality and safety metric. Although most LWBS cases involve low-acuity presentations, some may have time-sensitive conditions, leading to delayed diagnoses, adverse outcomes, and increased healthcare utilization. To determine the prevalence, characteristics, and predictors of LWBS over a multi-year period in a high-volume tertiary ED in Türkiye.Methods This retrospective case–control study included all adult ED visits between 1 January 2020, and 30 June 2025, at Taksim Training and Research Hospital. LWBS cases were identified from electronic medical records and compared with controls presenting during the same timeframes. Demographic, triage, temporal, and operational factors were analyzed, and binary logistic regression identified independent predictors.Results From a total of 1,058,817 adult emergency department (ED) visits during the study period, 9,737 LWBS cases were identified, corresponding to an overall LWBS incidence of 1.0%. Annual LWBS counts ranged from 1,447 (14.9%) in 2020 to a peak of 2,995 (30.8%) in 2022, before declining to 450 (4.6%) in 2024. Patients who left without being seen were younger (mean 36.1 ± 15.0 years) and predominantly male (61.6%).The highest frequency of LWBS occurred during the evening shift (16:00–00:00) and among green-triage patients, with multivariable analysis confirming increased odds in these groups (evening shift OR = 4.99; 95% CI, 3.18–8.09). Night-shift presentations were associated with reduced LWBS risk (OR = 0.54; p < 0.001).Conclusion Younger age, evening presentation, and triage category were associated with LWBS in this high-volume tertiary emergency department. However, the predictive performance of the regression model was modest (AUC = 0.584), suggesting that additional patient-related, behavioral, and system-level factors may contribute to LWBS. Further studies are needed to better understand the determinants of this phenomenon.