Circadian Rhythm of Hospital Death: Difference Between the Intensive Care Unit and General Room

Background and Objectives: The purpose was to record the time at which biological phenomena stop in different hospital wards and determine regular patterns in times of death, as well as any associated factors. Subjects and Methods: A total of 6,517 inpatients at the Keimyung University Dongsan Medical Center who died between January 2006 and December 2012 were retrospectively enrolled. A comparative analysis was conducted for the mortality distribution between the intensive care unit (ICU) and general wards (GW). Results: A total of 3,198 (49%) died in the ICU and 3,319 (51%) in the GW. The ICU showed an increase in mortality over the most recent 3 years. There was no difference in monthly or daily pattern. ICU mortality peaked at 14:00 to 16:00 hours (9.2%) and 20:00 to 22:00 hours (9.1%), and GW mortality peaked at 06:00 to 08:00 hours (9.6%) and 10:00 to 12:00 hours (9.4%), with a significant statistical difference between the two wards (p=0.03). Patients with diseases of the circulatory system died most often in the ICU (28.3%), whereas those with neoplasms had the highest mortality rate in the GW (77.7%) (p<0.01). Conclusion: Some differences between the ICU and GW may be accounted for by a preserved circadian rhythm that was affected by disease distribution, hospital room environment, and use of various drugs.