The probability of readmission within 30 days of hospital discharge is positively associated with inpatient bed occupancy at discharge – a retrospective cohort study

Mathias C. Blom, Karin Erwander, Lars Gustafsson, Mona Landin-Olsson, Fredrik Jonsson, Kjell Ivarsson

Previous work has suggested that given a hospital's need to admit more patients from the emergency department (ED), high inpatient bed occupancy may encourage premature hospital discharges that favor the hospital's need for beds over patients' medical interests. We argue that the effects of such action would be measurable as a greater proportion of unplanned hospital readmissions among patients discharged when the hospital was full than when not. In response, the present study tested this hypothesis by investigating the association between inpatient bed occupancy at the time of hospital discharge and the 30-day readmission rate. The sample included all inpatient admissions from the ED at a 420-bed emergency hospital in southern Sweden during 2011-2012 that resulted in discharge before 1 December 2012. The share of unplanned readmissions within 30 days was computed for levels of inpatient bed occupancy of <95 %, 95-100 %, 100-105 % and >105 % at the hour of discharge. A binary logistic regression model was constructed to adjust for age, time of discharge, and other factors that could affect the outcome. In all, 32,811 visits were included in the study, 9.9 % of which resulted in an unplanned readmission within 30 days of discharge. The proportion of readmissions was 9.0 % for occupancy levels of <95 % at the patient's discharge, 10.2 % for 95-100 % occupancy, 10.8 % for 100-105 % occupancy, and 10.5 % for >105 % occupancy (p = 0.0001). Results from the multivariate models show that the OR (95 % CI) of readmission was 1.11 (1.01-1.22) for patients discharged at 95-100 % occupancy, 1.17 (1.06-1.29) at 100-105 % occupancy, and 1.15 (0.99-1.34) at >105 % occupancy. Results indicate that patients discharged from inpatient wards at times of high inpatient bed occupancy experience an increased risk of unplanned readmission within 30 days of discharge.