Mortality related to after-hours discharge from intensive care in Australia and New Zealand, 2005-2012

After-hours discharge from the intensive care unit (ICU) is associated with adverse patient outcomes including increased ICU readmissions and mortality. Since Australian and New Zealand data were last published, overall ICU patient mortality has decreased; however it is unknown whether changes in discharge practices have contributed to these improved outcomes. Our aim was to examine trends over time in discharge timing and the contemporary associations with mortality and ICU readmission. Retrospective cohort study using data from the Australian and New Zealand Intensive Care Society Adult Patient Database (ANZICS APD) for patients admitted to Australian and New Zealand ICUs between January 2005 and December 2012. Data collected included patient characteristics, time of ICU discharge, hospital mortality and ICU readmissions. Between 1 January 2005 and 31 December 2012, there were 710,535 patients available for analysis, of whom 109,384 (15.4 %) were discharged after-hours (1800-0600 hours). There were no changes in timing of ICU discharge over the 8 years of the study. Patients discharged after-hours had a higher hospital mortality (6.4 versus 3.6 %; P < 0.001) and more ICU readmissions (5.1 versus 4.5 %; P < 0.001) than patients discharged in-hours. Although post-ICU mortality for all patients declined during the study period, the risk associated with after-hours discharge remained elevated throughout (odds ratio 1.34, 95 % confidence intervals 1.30-1.38). After-hours discharge remains an important independent predictor of hospital mortality and readmission to ICU. Despite widespread dissemination this evidence has not translated into fewer after-hours discharges or reduction in risk in Australian and New Zealand hospitals.