Original Articles
SNAP-II and SNAPPE-II: Simplified newborn illness severity and mortality risk scores,☆☆

Presented in the form of 3 abstracts at the Pediatric Academic Societies meeting in New Orleans, La, May 2-3, 1998.
https://doi.org/10.1067/mpd.2001.109608Get rights and content

Abstract

Objectives: Illness severity scores for newborns are complex and restricted by birth weight and have dated validations and calibrations. We developed and validated simplified neonatal illness severity and mortality risk scores. The primary outcome was in-hospital mortality. Study design: Thirty neonatal intensive care units in Canada, California, and New England collected data on all admissions during the mid 1990s; patients moribund at birth or discharged to normal newborn care in <24 hours were excluded. Starting with the 34 data elements of the Score for Neonatal Acute Physiology (SNAP), we derived the most parsimonious logistic model for in-hospital mortality using 10,819 randomly selected Canadian cases. SNAP-II includes 6 physiologic items; to this are added points for birth weight, low Apgar score, and small for gestational age to create a 9-item SNAP-Perinatal Extension-II (SNAPPE-II). We validated SNAPPE-II on the remaining 14,610 cases and optimized the calibration. Results: In all birth weights, SNAPPE-II had excellent discrimination and goodness of fit. Area under the receiver operator characteristic curve was.91 ± 0.01. Goodness of fit (Hosmer-Lemeshow) was 0.90. Conclusions: SNAP-II and SNAPPE-II are empirically validated illness severity and mortality risk scores for newborn intensive care. They are simple, accurate, and robust across populations. (J Pediatr 2001;138:92-100)

Section snippets

POPULATION SELECTION

We assembled a consortium of 3 independent neonatal research networks (Table I) whose investigators had implemented SNAP as part of their ongoing data collection.We prospectively ensured compatibility of key data elements and study protocols and shared updates throughout. We collected data on all sequential admissions of infants of all birth weights during the designated study periods; we excluded: (1) babies released to the regular nursery in <24 hours; (2) babies admitted to the neonatal

Population

The New England cohort was enriched in very low birth weight cases because 4 of their sites collected data for only babies <1500 g or <32 weeks’ gestational age (Table I). This affected the birth weight distribution, the baseline illness severity as measured by the original SNAP, and the incidence of SGA and low Apgar scores. The “split half” Canadian cohorts appear fully comparable. The Kaiser Permanente cohort tended to have the lowest proportion of smaller, sicker infants. The 20% “outborn”

Discussion

This 30-site study, involving 25,429 newborns, has derived and validated SNAP-II as a measure of newborn illness severity and the SNAPPE-II as a measure of mortality risk. The new scores apply to babies of all birth weights and are simple, rapid, and accurate. It is now feasible to readily incorporate these measures of illness severity and mortality risk into routine databases23 to enhance their utility in outcomes measurement and bench marking.24

The construction of scoring systems uses both

Acknowledgements

We thank Robert Parker for advice on statistical analysis and Lynn Chien for her analyses. John D. Corcoran is currently consultant pediatrician and neonatologist at the Rotunda Hospital in Dublin, Ireland. We also thank all investigators and project staffs of the respective networks.

For the 17 sites in the Canadian NICU Network these include: Wayne Andrews, MD, FRCPC (Charles A. Janeway Child Health Centre, St John’s, NF); Ranjit Baboolal, MD, FRCPC (North York Hospital, North York, ON); Jill

References (30)

  • DK Richardson et al.

    Measuring illness severity in newborn intensive care

    J Intensive Care Med

    (1994)
  • DK Richardson et al.

    Neonatal risk scoring systems. Can they predict mortality and morbidity?

    Clin Perinatol

    (1998)
  • D Richardson et al.

    Risk adjustment for quality improvement

    Pediatrics

    (1999)
  • MM Pollack et al.

    PRISM III: an updated Pediatric Risk of Mortality score

    Crit Care Med

    (1996)
  • MM Pollack et al.

    Pediatric risk of mortality (PRISM) score

    Crit Care Med

    (1988)
  • Cited by (931)

    View all citing articles on Scopus

    Supported by the Medical Research Council of Canada (MRC grants No. CAAA-40503 and No. 1520); North York General Hospital Foundation; Midland Walwyn Capital Inc; Division of Neonatology, Children’s Hospital of Eastern Ontario; Child Health Program, Health Care Corporation of St John’s; St Joseph’s Health Centre; Lawson Research Institute; University of Western Ontario; Mount Sinai Hospital; Hospital for Sick Children; Women’s College Hospital; Division of Neonatology, Chedoke McMaster Hospital; B.C. Children’s Hospital Foundation; Kaiser Foundation Health Plan, Inc; and The Permanente Medical Group, Inc. Data collection on the New England cohort was performed as part of a grant from the Agency for Health Care Policy and Research (RO1 HS07015).

    ☆☆

    Reprint requests: Douglas K. Richardson, MD, MBA, Beth Israel Deaconess Medical Center, Department of Neonatology, 330 Brookline Ave, Boston MA 02215.

    View full text