Later emergency provider shift hour is associated with increased risk of admission: a retrospective cohort study

Background Understanding factors that drive admissions is critical to containing cost and optimising hospital operations. We hypothesised that, due to multiple factors, emergency physicians would be more likely to admit a patient seen later in their shift. Methods Retrospective study examining all patient visits at a large academic hospital from July 2010 to July 2016. Patients with missing data (n=191) were excluded. 294 031 emergency department (ED) visits were included in the final analysis. The exposure of interest was the time during the shift at which a patient was first evaluated by the clinician, and outcome was hospital admission. We used a generalised estimating equation with physician as the clustering level to adjust for patient age, gender, Emergency Severity Index (ESI, 1=most severe illness, 5=least severe illness) and 24 hours clock time. We also conducted a stratified analysis by three ESI categories. Results From the 294 031 ED visits, 5977 were seen in the last hour of the shift. Of patients seen in the last shift hour, 43% were admitted versus 39% seen at any other time during the shift. There was a significant association between being evaluated in the last hour (RR 1.03, 95% CI 1.01 to 1.06) and last quarter (RR 1.02, 1.01 to 1.03) of shift and the likelihood of admission. Patients with an ESI Score of 4–5 saw the largest effect sizes (RR 1.62, 0.996–2.635 for last hour and RR 1.24, 0.996–1.535 for last quarter) but these were not statistically significant. Additionally, there was a trend towards increased likelihood of admission later in shift; the relative risk of admission was 1.04 in hour 6, (1.02–1.05), 1.03 in hour 7 (1.01–1.05), 1.04 in hour 8 (1.01–1.06) and 1.06 in hour 9 (1.013–1.101). Conclusions There is a small but significant association between a patient being evaluated later in an emergency physician’s shift and their likelihood of being admitted to the hospital.