Outcomes of Prolonged ICU Stay for Patients Undergoing Cardiac Surgery in Australia and New Zealand

Abstract

Objective: To determine the effect of intensive care unit (ICU) length of stay (LOS) on hospital mortality and non-home discharge for patients undergoing cardiac surgery over a 16-year period in Australia and New Zealand.

Design: A retrospective, multicenter cohort study covering the period January 1, 2004 to December 31, 2019.

Setting: One hundred one hospitals in Australia and New Zealand that submitted data to the Australia New Zealand Intensive Care Society Adult Patient Database.

Participants: Adult patients (aged >18) who underwent coronary artery bypass grafting, valve surgery, or combined valve + coronary artery surgery.

Interventions: None.

Measurements and main results: The authors analyzed 252,948 cardiac surgical patients from 101 hospitals, with a median age of 68.3 years (IQR 60-75.5), of whom 74.2% (187,632 of 252,948) were male patients. A U-shaped relationship was observed between ICU LOS and hospital mortality, with significantly elevated mortality at short (<20 hours) and long (>5 days) ICU LOS, which persisted after adjustment for illness severity and across clinically important subgroups (odds ratio for mortality with ICU LOS >5 days = 3.21, 95% CI 2.88-3.58, p < 0.001).

Conclusions: Prolonged duration of ICU LOS after cardiac surgery is associated with increased hospital mortality in a U-shaped relationship. An ICU LOS >5 days should be considered a meaningful definition for prolonged ICU stay after cardiac surgery.

Keywords: cardiac surgery; critical care; hospital mortality; intensive care; length of stay; non-home discharge.