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

•Grouped patients that were admitted to the same hospital and time periods.•Compared grouped patients that were exposed to more and less busy circumstances.•No detectable effects of hospital busyness on mortality or readmissions.•Discharge process was affected.•Higher risk of being discharged outside daytime working hours.