Readmissions to Intensive Care: A Prospective Multicenter Study in Australia and New Zealand.

Abstract

To determine factors independently associated with readmission to ICU and the independent association of readmission with subsequent mortality. Prospective multicenter observational study. Forty ICUs in Australia and New Zealand. Consecutive adult patients discharged alive from ICU to hospital wards between September 2009 and February 2010. Measurement of hospital mortality. We studied 10,210 patients and 674 readmissions. The median age was 63 years (interquartile range, 49-74), and 6,224 (61%) were male. The majority of readmissions were unplanned (84.1%) but only deemed preventable in a minority (8.9%) of cases. Time to first readmission was shorter for unplanned than planned readmission (3.2 vs 6.9 d; p < 0.001). Primary diagnosis changed between admission and readmission in the majority of patients (60.2%) irrespective of planned (58.2%) or unplanned (60.6%) status. Using recurrent event analysis incorporating patient frailty, we found no association between readmissions and hospital survival (hazard ratios: first readmission 0.88, second readmission 0.90, third readmission 0.44; p > 0.05). In contrast, age (hazard ratio, 1.03), a medical diagnosis (hazard ratio, 1.43), inotrope use (hazard ratio, 3.47), and treatment limitation order (hazard ratio, 17.8) were all independently associated with outcome. In this large prospective study, readmission to ICU was not an independent risk factor for mortality.