CRIB-2 Score Calculation
The CRIB-2 (Clinical Risk Index for Babies-2) score is calculated within the first hour of birth using five variables: gestational age, birth weight, sex, admission temperature, and base excess from arterial blood gas.
Score Components
The CRIB-2 scoring system assigns points based on the following parameters 1, 2:
Variables Used:
- Gestational age (in completed weeks)
- Birth weight (in grams)
- Sex (male vs. female)
- Admission temperature (measured within first hour)
- Base excess (from arterial blood gas, worst value in first hour)
Clinical Application
This score must be calculated within 1 hour of birth to maintain its validated predictive accuracy 1. The total score ranges from 1 to approximately 19 points, with higher scores indicating greater mortality risk 2.
Risk Stratification:
Multiple studies have established mortality prediction thresholds:
- CRIB-2 score ≥10-11 is associated with significantly increased mortality risk 2, 3
- The score demonstrates excellent discriminative ability with area under ROC curve of 0.87-0.97 1, 2, 4
- Sensitivity ranges from 85-95% and specificity from 82-96% for mortality prediction 2, 4, 3
Target Population
The CRIB-2 score is specifically designed for:
- Preterm infants ≤32-34 weeks gestational age 1, 3
- Low birth weight babies (typically <1500g) 1, 2
- Very low birth weight infants 5
Predictive Performance
CRIB-2 outperforms gestational age or birth weight alone in predicting neonatal mortality 1, 2. The score demonstrates:
- Best predictive accuracy within the first 90 days of life (AUC 0.84) 5
- Good calibration for mortality prediction (Hosmer-Lemeshow p=0.952) 2
- Progressive mortality increase with higher scores: 0% mortality at level I, 3.84% at level II, 64.70% at level III, and 100% at level IV 4
Important Caveat:
A modified version (CRIB II-BE) that excludes base excess shows similar predictive performance 5, which may be useful when arterial blood gas is not immediately available, though the standard CRIB-2 with all five variables remains the validated tool.