Threat of COVID-19 impacting on a quaternary healthcare service: a retrospective cohort study of administrative data

ObjectivesThe threat of a pandemic, over and above the disease itself, may have significant and broad effects on a healthcare system. We aimed to describe the impact of the SARS-CoV-2 pandemic (during a relatively low transmission period) and associated societal restrictions on presentations, admissions and outpatient visits.DesignWe compared hospital activity in 2020 with the preceding 5 years, 2015–2019, using a retrospective cohort study design.SettingQuaternary hospital in Melbourne, Australia.ParticipantsEmergency department presentations, hospital admissions and outpatient visits from 1 January 2015 to 30 June 2020, n=896 934 episodes of care.InterventionIn Australia, the initial peak COVID-19 phase was March–April.Primary and secondary outcome measuresSeparate linear regression models were fitted to estimate the impact of the pandemic on the number, type and severity of emergency presentations, hospital admissions and outpatient visits.ResultsDuring the peak COVID-19 phase (March and April 2020), there were marked reductions in emergency presentations (10 389 observed vs 14 678 expected; 29% reduction; p