Impact of intensive care unit discharge time on patient outcome

Objective To determine the impact of nighttime intensive care unit (ICU) discharge on patient outcome. Design Multiple-center, retrospective observational cohort study. Setting Canadian hospitals. Patients We used a prospectively collected dataset containing information on 79,090 consecutive admissions from 31 Canadian community and teaching hospitals. Interventions None. Measurements and main results Patients were categorized according to the time of ICU discharge into daytime (07:00-20:59) and nighttime (21:00-06:59). Admissions were excluded if the patients were a) </=16 yrs of age (392); b) admitted following cardiac surgery (6,641); c) admitted following the initial admission for patients readmitted to the ICU within the same hospital stay (3,632); d) admitted due to a lack of available ward or specialty care beds (457); or c) transferred to another acute care facility (7,724). We found that 62,056 patients were discharged to the ward following the initial ICU admission. Of the 47,062 discharges eligible for analyses, 10.1% were discharged at night. The unadjusted odds of death for patients discharged from ICU at night was 1.35 (95% confidence interval, 1.23, 1.49), compared with patients discharged during the daytime. After adjustment for illness severity, source, case-mix, age, gender, and hospital size, the mortality risk was increased by 1.22-fold (95% confidence interval, 1.10, 1.36) for nighttime discharges. Multivariate regression analysis revealed that patients discharged from the ICU at night have a significantly shorter ICU length of stay than those discharged during the day (p < .001). Whereas hospital length of stay was similar for daytime and nighttime discharges who survived hospital stay, patients discharged at night who did not survive hospital stay had a significantly shorter hospital length of stay (p = .002). Conclusions Patients discharged from the ICU at night have an increased risk of mortality compared with those discharged during the day.