BACKGROUND: The Acute Medical Unit (AMU) provides care for unscheduled hospital admissions . Seven-day Consultant presence and morning AMU discharges have been advocated to improve hospital bed management .

AIMS: To determine whether a later time of daily peak AMU occupancy correlates with measures of hospital stress; whether seven-day Consultant presence, for COVID-19, abolished weekly periodicity of discharges .

DESIGN: Retrospective cohort analysis .

METHODS: Anonymised AMU admission and discharge times were retrieved from the Profile Information Management System (PIMS), at a large, urban hospital from 14th April 2014-31st December 2018 and 20th March-2nd May 2020 (COVID-19 peak). Minute-by-minute admission and discharge times were combined to construct a running total of AMU bed occupancy . Fourier transforms were used to determine periodicity . We tested association between i) average AMU occupancy and ii) time of peak AMU occupancy, with measures of hospital stress (total medical bed occupancy and 'medical outliers' on non-medical wards).

RESULTS: Daily, weekly and seasonal patterns of AMU bed occupancy were evident . Timing of AMU peak occupancy was unrelated to each measure of hospital stress: total medical inpatients (Spearman's rho, rs=0.04, P = 0.24); number of medical outliers (rs=-0.06, P = 0.05). During COVID-19, daily bed occupancy was similar, with continuation of greater Friday and Monday discharges than the weekend .

CONCLUSIONS: Timing of peak AMU occupancy did not alter with hospital stress . Efforts to increase morning AMU discharges are likely to have little effect on hospital performance . Seven-day Consultant presence did not abolish weekly periodicity of discharges - other factors influence weekend discharges.