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Variation in Adjusted Mortality for Medical Admissions to Pediatric Cardiac ICUs*

Gaies, Michael, MD1,2; Ghanayem, Nancy S., MD3; Alten, Jeffrey A., MD4; Costello, John M., MD5; Lasa, Javier J., MD3; Chanani, Nikhil K., MD6; Shin, Andrew Y., MD7; Retzloff, Lauren, MPH8; Zhang, Wenying, MS2,8; Pasquali, Sara K., MD1,2; Banerjee, Mousumi, PhD2,9; Tabbutt, Sarah, MD, PhD10

Pediatric Critical Care Medicine: February 2019 - Volume 20 - Issue 2 - p 143–148
doi: 10.1097/PCC.0000000000001751
Cardiac Intensive Care

Objectives: Pediatric cardiac ICUs should be adept at treating both critical medical and surgical conditions for patients with cardiac disease. There are no case-mix adjusted quality metrics specific to medical cardiac ICU admissions. We aimed to measure case-mix adjusted cardiac ICU medical mortality rates and assess variation across cardiac ICUs in the Pediatric Cardiac Critical Care Consortium.

Design: Observational analysis.

Setting: Pediatric Cardiac Critical Care Consortium clinical registry.

Patients: All cardiac ICU admissions that did not include cardiac surgery.

Interventions: None.

Measurements and Main Results: The primary endpoint was cardiac ICU mortality. Based on multivariable logistic regression accounting for clustering, we created a case-mix adjusted model using variables present at cardiac ICU admission. Bootstrap resampling (1,000 samples) was used for model validation. We calculated a standardized mortality ratio for each cardiac ICU based on observed-to-expected mortality from the fitted model. A cardiac ICU was considered a statistically significant outlier if the 95% CI around the standardized mortality ratio did not cross 1. Of 11,042 consecutive medical admissions from 25 cardiac ICUs (August 2014 to May 2017), the observed mortality rate was 4.3% (n = 479). Final model covariates included age, underweight, prior surgery, time of and reason for cardiac ICU admission, high-risk medical diagnosis or comorbidity, mechanical ventilation or extracorporeal membrane oxygenation at admission, and pupillary reflex. The C-statistic for the validated model was 0.87, and it was well calibrated. Expected mortality ranged from 2.6% to 8.3%, reflecting important case-mix variation. Standardized mortality ratios ranged from 0.5 to 1.7 across cardiac ICUs. Three cardiac ICUs were outliers; two had lower-than-expected (standardized mortality ratio <1) and one had higher-than-expected (standardized mortality ratio >1) mortality.

Conclusions: We measured case-mix adjusted mortality for cardiac ICU patients with critical medical conditions, and provide the first report of variation in this quality metric within this patient population across Pediatric Cardiac Critical Care Consortium cardiac ICUs. This metric will be used by Pediatric Cardiac Critical Care Consortium cardiac ICUs to assess and improve outcomes by identifying high-performing (low-mortality) centers and engaging in collaborative learning.

1Department of Pediatrics and Communicable Diseases, C.S. Mott Children’s Hospital and University of Michigan Medical School, Ann Arbor, MI.

2Center for Health Outcomes and Policy & Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor, MI.

3Department of Pediatrics, Texas Children’s Hospital & Baylor College of Medicine, Houston, TX.

4Department of Pediatrics and The Heart Institute, Cincinnati Children’s Hospital Medical Center and University of Cincinnati College of Medicine, Cincinnati, OH.

5Department of Pediatrics, Ann & Robert H. Lurie Children’s Hospital of Chicago and Northwestern University Feinberg School of Medicine, Chicago, IL.

6Department of Pediatrics and Sibley Heart Center, Emory University and Children’s Healthcare of Atlanta, Atlanta, GA.

7Department of Pediatrics, Lucille Packard Children’s Hospital and Stanford University School of Medicine, Palo Alto, CA.

8Michigan Congenital Heart Outcomes Research and Discovery, PC4 Data Coordinating Center, University of Michigan, Ann Arbor, MI.

9Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, MI.

10Department of Pediatrics, University of California San Francisco School of Medicine and Benioff Children’s Hospital, San Francisco, CA.

*See also p. 194.

Lauren Retzloff is now Lauren Bush.

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 funding from the University of Michigan Congenital Heart Center, CHAMPS for Mott, and the Michigan Institute for Clinical & Health Research (National Institutes of Health/NCATS UL1TR002240).

Dr. Gaies received support for article research from the National Institutes of Health/National Heart, Lung, and Blood Institute (K08HL116639). Dr. Costello disclosed that he has served on Pediatric Cardiac Critical Care Consortium’s Executive Committee for the last 5–6 year (unpaid, volunteer position). Ms. Zhang disclosed work for hire. Dr. Pasquali receives support from the Janette Ferrantino Professorship. The remaining authors have disclosed that they do not have any potential conflicts of interest.

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©2019The Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies