Hierarchical Classification of Clinical Signsa

Clinical PresentationbDescription
Clinical illnessIn the first 12 h of age, the infant had a 5-min Apgar <5; received nasal continuous positive airway pressure or mechanical ventilation; received continuous infusion of vasoactive drugs; had a clinical seizure; or had significant respiratory distress (nasal flaring, grunting, or retractions were present and the infant received supplemental oxygen within the first 6 h)
Equivocal presentationIn the first 12 h of age, the infant experienced at least 2 instances of 1 of the following, with “instance”c meaning that there were ≥2 measurements ≥2 h apart:
  Heart rate ≥160
  Respiratory rate ≥60
  Temperature ≥100.4°F or <97.5°F
  Respiratory distress (grunting, flaring, or retracting)
Well appearingThe infant did not fall into one of the above 2 groups in the first 12 h of age
  • a Clinical presentations shown in the table are mutually exclusive and the scheme is applied sequentially, with infants removed from the group before applying the next category.

  • b To quantify the duration of clinical instability and avoid classifying infants based on transient abnormalities, we used the concept of “instance” for vital signs and respiratory distress (grunting, flaring, or retractions). An instance was the occurrence of a second abnormal value at least 2 hours after the first occurrence of an abnormal index value. Abnormal values after the index measurement counted as a new instance if they were followed by another abnormal measurement at least 2 hours later. Instances were sign-specific (ie, an abnormal temperature followed by an abnormal respiratory rate 2.1 hours later would not count as an instance for either temperature or respiratory rate).

  • c See text, Supplemental Information, and reference 2 for a description of data collection protocol.