Objectives: To test the performance of the Glasgow Admission Prediction Score (GAPS) and Ambulatory Score (Amb score), and derive and validate a novel score for the identification of Emergency Department (ED) attendances suitable for treatment by Same Day Emergency Care (SDEC) services. Design: Retrospective diagnostic study using routinely collected data from electronic healthcare records. Setting: Three hospitals in the diverse urban setting of Birmingham, UK, between April 2023-March 2024. Participants: Adult patients with an unplanned hospital attendance requiring internal medicine assessment. Main Outcome Measures: Suitability for treatment by SDEC services, defined as being discharged alive with a length of stay of <12 hours (LOS<12). Results: Data were included for 152,877 attendances, with a median age of 58 years (interquartile range: 38 to 76), and of which 54.3% were by female patients and 68.4% of White ethnicity; the outcome of LOS<12 was achieved in 45.0% (N=68,752). The GAPS and Amb score had moderate predictive accuracy, with areas under the receiver operating characteristic curve (AUROCs) of 0.741 (95% CI: 0.738 to 0.744) and 0.733 (95% CI: 0.730 to 0.736), respectively. A novel score was produced, comprising the factors from the GAPS and Amb score, as well as the National Early Warning Score 2 (NEWS2) and primary presenting complaint. When applied to an internal validation set (N=27,078), the resulting SDEC Triage Tool (SDEC-T) achieved an AUROC of 0.850 (95% CI: 0.845 to 0.854), with performance being similar across the three hospitals (AUROC range: 0.845 to 0.858). Conclusions: The novel score derived within this diverse cohort has superior accuracy to the existing Amb score and GAPS for the identification of patients suitable for treatment in SDEC.

C. Atkin, J. Hodson, F. Evison, L. Li and V. Reddy-Kolanu report no conflicts of interest. S Gallier reports funding support from HDRUK, MRC and NIHR. E Sapey reports funding support from HDRUK, MRC, Wellcome Trust, EPSRC and NIHR.

This study is funded by the National Institute for Health and Care Research (NIHR) Midlands Patient Safety Research Collaboration (PSRC) and NIHR Midlands Patient Safety Research Collaboration (PSRC) and the NIHR Applied Research Collaboration (ARC) West Midlands and NIHR Birmingham Biomedical Research Centre. The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.

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The study was approved by the East Derby Research Ethics Committee (reference 20/EM/0158) and Health Research Authority (reference number 279353).

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