SNAP-II for prediction of mortality and morbidity in extremely preterm infants

Abstract

Objective: To determine the specific Score of Neonatal Acute Physiology (SNAP-II) cut-off scores associated with outcomes in extremely preterm infants, and to examine its contribution to predictive models that include nonmodifiable birth predictors.

Study design: Retrospective observational study of 9240 infants born at 22–28 weeks’ gestation and admitted to the Canadian Neonatal Network from 2010 to 2015. Outcomes included early and hospital mortality, composite of mortality/morbidity and individual morbidities. The SNAP-II cut-off to predict each outcome was determined using the Youden index. Additional contributions were evaluated using a base model that adjusted for gestational age, birth weight z-score and sex and by comparing the area under the curve (AUC).

Results: The mortality/morbidity rate was 63% (5859/9240). Specific SNAP-II cut-offs ranged from 12 to 20 and were associated with each adverse outcome. Adding SNAP-II cut-offs to predictive models that included birth variables significantly improved (p < .05) the prediction of early mortality (AUC 0.84 versus 0.79), hospital mortality (AUC 0.80 versus 0.78), mortality/morbidity (AUC 0.76 versus 0.75), and severe neurological injury (AUC 0.69 versus 0.66) but had little or no effect on predictive models for retinopathy of prematurity, bronchopulmonary dysplasia, necrotizing enterocolitis, and nosocomial infection.

Conclusions: SNAP-II cut-offs were independently associated with each adverse outcome and using the proposed SNAP-II cut-offs improved the performance of predictive models for certain short-term outcomes.

Keywords:

• Infant
• premature
• illness severity
• predictive value of tests
• morbidity/mortality

Acknowledgements

We thank the staff of the Canadian Neonatal Network (CNN) Coordinating Centre. Although no funding was received specifically for this study, the CNN Coordinating Centre is based at the Maternal-Infant Care Research Centre (MiCare) at Mount Sinai Hospital, Toronto, Ontario, Canada. MiCare is supported by grant funding from the Canadian Institutes of Health Research and in-kind support from Mount Sinai Hospital, Toronto.

Site investigators for the Canadian Neonatal Network

Prakesh S. Shah, MD, MSc (Director, Canadian Neonatal Network and site investigator), Mount Sinai Hospital, Toronto, Ontario; Jaideep Kanungo, MD, Victoria General Hospital, Victoria, British Columbia; Joseph Ting, MD, B.C. Women’s Hospital and Health Centre, Vancouver, British Columbia; Zenon Cieslak, MD, Royal Columbian Hospital, New Westminster, British Columbia; Rebecca Sherlock, MD, Surrey Memorial Hospital, Surrey, British Columbia; Wendy Yee, MD, Foothills Medical Centre, Calgary, Alberta; Jennifer Toye, MD, Royal Alexandra Hospital, Edmonton, Alberta; Carlos Fajardo, MD, Alberta Children’s Hospital, Calgary, Alberta; Zarin Kalapesi, MD, Regina General Hospital, Regina, Saskatchewan; Koravangattu Sankaran, MD, MBBS, and Sibasis Daspal, MD, Royal University Hospital, Saskatoon, Saskatchewan; Mary Seshia, MBChB, Winnipeg Health Sciences Centre, Winnipeg, Manitoba; Ruben Alvaro, MD, St. Boniface General Hospital, Winnipeg, Manitoba; Amit Mukerji, MD, Hamilton Health Sciences Centre, Hamilton, Ontario; Orlando Da Silva, MD, MSc, London Health Sciences Centre, London, Ontario; Chuks Nwaesei, MD, Windsor Regional Hospital, Windsor, Ontario; Kyong-Soon Lee, MD, MSc, Hospital for Sick Children, Toronto, Ontario; Michael Dunn, MD, Sunnybrook Health Sciences Centre, Toronto, Ontario; Brigitte Lemyre, MD, Children’s Hospital of Eastern Ontario and Ottawa General Hospital, Ottawa, Ontario; Kimberly Dow, MD, Kingston General Hospital, Kingston, Ontario; Ermelinda Pelausa, MD, Jewish General Hospital, Montréal, Québec; Keith Barrington, MBChB, and Anie Lapoint, MD, Hôpital Sainte-Justine, Montréal, Québec; Christine Drolet, MD, and Bruno Piedboeuf, MD, Centre Hospitalier Universitaire de Québec, Sainte-Foy, Québec; Martine Claveau, MSc, LLM, NNP, and Marc Beltempo, MD, Montreal Children’s Hospital at McGill University Health Centre, Montréal, Québec; Valerie Bertelle, MD, and Edith Masse, MD, Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Québec; Roderick Canning, MD, Moncton Hospital, Moncton, New Brunswick; Hala Makary, MD, Dr. Everett Chalmers Hospital, Fredericton, New Brunswick; Cecil Ojah, MBBS, and Luis Monterrosa, MD, Saint John Regional Hospital, Saint John, New Brunswick; Julie Emberley, MD, Janeway Children’s Health and Rehabilitation Centre, St. John’s, Newfoundland; Jehier Afifi, MB BCh, MSc, IWK Health Centre, Halifax, Nova Scotia; Andrzej Kajetanowicz, MD, Cape Breton Regional Hospital, Sydney, Nova Scotia; Shoo K. Lee, MBBS, PhD (Chairman, Canadian Neonatal Network), Mount Sinai Hospital, Toronto, Ontario.

Disclosure statement

The funding agencies had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript; and decision to submit the manuscript for publication. Prakesh Shah holds an Applied Research Chair in Reproductive and Child Health Services and Policy Research awarded by the Canadian Institutes of Health Research. The remaining authors declare no conflict of interest.