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

Santamaria, John D. MBBS, MD, FRACP, FCICM, FCCP; Duke, Graeme J. MBBS, FCICM, FANZCA; Pilcher, David V. FCICM, FRACP, MRCP; Cooper, D. James MBBS, MD, FCICM; Moran, John MBBS, MD, FRACP, FCICM, FANZCA; Bellomo, Rinaldo MD, FRACP, FCICM

doi: 10.1097/CCM.0000000000002066
Late Breaker Article

Objectives: To determine factors independently associated with readmission to ICU and the independent association of readmission with subsequent mortality.

Design: Prospective multicenter observational study.

Setting: Forty ICUs in Australia and New Zealand.

Patients: Consecutive adult patients discharged alive from ICU to hospital wards between September 2009 and February 2010.

Interventions: Measurement of hospital mortality.

Measurements and Main Results: 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.

Conclusions: In this large prospective study, readmission to ICU was not an independent risk factor for mortality.

Supplemental Digital Content is available in the text.

1Department of Critical Care Medicine, St Vincent’s Hospital (Melbourne), Fitzroy, VIC, Australia.

2Intensive Care Unit, Eastern Health (Box Hill Hospital), Box Hill, VIC, Australia.

3Intensive Care Unit, The Alfred Hospital and ANZIC Research Centre Monash University, Melbourne, VIC, Australia.

4Intensive Care Unit, The Queen Elizabeth Hospital, Woodville South, SA, Australia.

5Australian and New Zealand Research Centre, Monash University, Melbourne, VIC, Australia.

*See also p. 378.

The data were collected by designated persons at each of the participating hospitals. In addition, a senior intensivist at each hospital held the position of chief investigator; this person provided a reference point for data collection.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (

Supported, in part, by grants from the Intensive Care Foundation of Australia and the Australian and New Zealand College of Anesthetists Foundation. This study was endorsed by the ANZICS Clinical Trials Group. Neither funder had input to the design nor conduct of the study, the collection or management or analysis or interpretation of the data, and no involvement with preparation or review or approval of the article.

Dr. Santamaria disclosed other support (employed by St Vincent’s Hospital Melbourne as intensive care specialist) and received support for article research from the Intensive Care Foundation (Australia, Australian and New Zealand Intensive Care [ANZIC]) and Australian and New Zealand College of Anaesthetists (ANZCA) Foundation. His institution received funding from the Intensive Care Foundation and ANZCA Foundation. Dr. Bellomo received support for article research from the ANZIC ICU Foundation. The remaining authors have disclosed that they do not have any potential conflicts of interest.

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