Damian McNamara

January 27, 2017

HONOLULU — Readmission to an intensive care unit is often used as a metric by regulators and agencies to gauge quality of care, but it is not an independent predictor of hospital mortality on its own, results from a large study of critical care outcomes reveal.

"The factors contributing to patient mortality were the illness of the patient and the age," John Santamaria, MD, intensive care specialist at the University of Melbourne in Australia, told Medscape Medical News. "Therefore, readmission to the ICU as a general indicator of ICU care is inappropriate."

Dr Santamaria and his colleagues evaluated 10,884 adults consecutively discharged from one of 40 intensive care units in Australia and New Zealand to a hospital ward from October 2009 to February 2010.

He presented the study results during a hot topics and late-breaking science session here at the Society of Critical Care Medicine 46th Critical Care Congress.

Most of the 581 (5.3%) patients readmitted to the ICU "required one more readmission, but a significant number came back multiple times," Dr Santamaria reported. The total number of readmissions was 674.

Table 1. ICU Readmissions and Hospital Mortality Risk

Readmission Hazard Ratio
First 0.88
Second 0.90
Third 0.44

Although readmissions are associated with increased mortality and an increased length of stay, "readmission per se is not a risk for mortality," Dr Santamaria explained.

"The first, second, and third readmissions were all not significant, so, in our view, hospital mortality is much more likely to be associated with patient factors," he said.

Table 2. Independent Risk Factors Associated With ICU Readmission

Risk Factor Hazard Ratio
Older age 1.03
Medical diagnosis 1.43
Use of inotropes 3.47
Treatment limitation order 17.8

"I wasn't surprised by the findings," Dr Santamaria acknowledged. "I always thought that patient factors were the main driver of mortality. One reason to do this study was to provide definitive evidence for this feeling."

Complete study results were published to coincide with Dr Santamaria's presentation in Critical Care Medicine (2017;45:290-297). In their report, his team notes that after adjustment "for these patient-related factors and for multiple ICU admissions, there was no independent statistical association between readmission to ICU and subsequent hospital mortality."

These findings "add fuel to the argument that readmission rates should not be viewed as a quality metric," said Timothy Buchman, PhD, MD, from Emory University Hospital in Atlanta.

Most unplanned admissions to the ICU are neither predictable nor preventable.

This study "confirms that most unplanned readmissions to the ICU are neither predictable nor preventable," he told Medscape Medical News.

Although this study was conducted in Australia and New Zealand, patterns are similar in the United States. "Readmissions bedevil and perplex intensive care units worldwide," Dr Buchman said.

In this study, 84% of the readmissions to the ICU were unplanned, and only 9% were considered preventable. Time to first readmission was significantly shorter for unplanned readmissions than for planned readmissions (3.2 vs 6.9 days; P < .001).

Median patient age was 63 years, 61% of the study population was male, and risk for death on first admission, according to median APACHE III score, was 9%. During the first admission, 56% of patients required mechanical ventilation, 42% needed inotropes, and 5% underwent renal replacement therapy. Overall, 5.2% died before hospital discharge.

Dr Santamaria has disclosed no relevant financial relationships. Dr Buchman is editor-in-chief of Critical Care Medicine, the journal in which the results were published.

Society of Critical Care Medicine (SCCM) 46th Critical Care Congress. Presented January 24, 2017.


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