How do busy hospital circumstances affect mortality and readmission within 60 days: A cohort study of 680 000 acute admissions in Norway.

Objective: To study mortality and readmissions for older patients admitted during more and less busy hospital circumstances.

Design: Cohort study where we identified patients that were admitted to the same hospital, during the same month and day of the week. We estimated effects of inflow of acute patients and the number of concurrent acute inpatients. Mortality and readmissions were analysed using stratified Cox-regression.

Setting: All people 80 years and older acutely admitted to Norwegian hospitals between 2008 and 2016.

Main Outcome Measures: Mortality and readmissions within 60 days from admission.

Results: Among 294 653 patients with 685 197 admissions, mean age was 86 years (standard deviation 5). Overall, 13% died within 60 days. An interquartile range difference in inflow of acute patients was associated with a hazard ratio (HR) of 0.99, 95% confidence interval (95% CI) 0.98 to 1.00). There was little evidence of differences in readmissions, but a 7% higher risk (HR 1.07, 95% CI 1.06 to 1.09) of being discharged outside ordinary daytime working hours.

Conclusions: Older patients admitted during busier circumstances had similar mortality and readmissions to those admitted during less busy periods. Yet, they showed a higher risk of discharge outside daytime working hours. Despite limited effects of busyness on a hospital level, there could still be harmful effects of local situations.