Does volume or occupancy influence emergency access block? A multivariate time series analysis from a single emergency department in Sydney, Australia during the COVID-19 pandemic

Objective: The study aims to determine whether ED presentation volume or hospital occupancy had a greater impact on ED performance before and during the COVID-19 health response at a tertiary referral hospital in Sydney, Australia. Methods: Single centre time series analysis using routinely collected hospital and ED data from January 2019 to September 2020. The primary outcome was ED access block measured by emergency treatment performance (ETP; i.e. percentage of patients who were discharged or transferred to a ward from ED within 4 h of ED arrival time). Secondary outcomes were hospital occupancy, elective theatre cases and ambulance ramping. Multivariate time series analysis was performed using vector autoregression, to model effects of changes in various endogenous and correlated variables on ETP. Results: There was an increase in ETP, drop in ED presentations and decrease in hospital occupancy between April and June 2020. Elective surgery and hospital occupancy had significant effects up to 2 days prior on ETP, while there were no significant effects of either ED or ambulance presentations on ETP. Hospital occupancy itself increased with ED presentations after 2-4 days and decreased with elective surgery after 1 day. Shocks (a one standard deviation increase) in hospital occupancy had a peak impact nearly two times greater compared to ED presentations (-1.43, 95% confidence interval -1.92, -0.93 vs -0.73, 95% confidence interval -1.21, -0.25). Conclusion: The main determinants of the reduction of ED overcrowding and access block during the pandemic were associated with reductions in hospital occupancy and elective surgery levels, and more research is required to assess more complex associations beyond the scope of this manuscript.

Automated summary

The study found that during the COVID-19 health response, hospital occupancy and elective surgery had a significant impact on ED performance, while the association with ED or ambulance presentations was not significant. The impact of hospital occupancy on ED performance was nearly twice that of ED presentations.