Birth weight and McGoon Index predict mortality in newborn infants with congenital diaphragmatic hernia.

BACKGROUND

Despite improvements in clinical management, mortality of congenital diaphragmatic hernia (CDH) remains high. Early prediction of mortality risk helps in comparing strategies and/or performances of different centers. Birth weight (BW), Apgar Score at 5 minutes, and modified McGoon Index (MGI) calculated by the ratio between the diameters of pulmonary arteries and the descending aorta have been used to determine mortality of CDH.

AIM

The purpose of this study is to evaluate the relationship between early detectable variables and survival in newborns with CDH intubated at birth, managed with "gentle" ventilation and delayed surgery.

METHODS

All medical records of patients affected by high-risk CDH and treated with a standardized protocol at Bambino Gesù Children's Hospital, Rome, Italy, between January 2002 and September 2004 were reviewed. Prenatal diagnosis, gestational age, BW, sex, side of hernia, and MGI were recorded on admission. The relationship with mortality of each variable was evaluated by univariate analysis. Subsequently, a predictive model of mortality was developed using a logistic regression: the explanatory variables, BW, and MGI were dichotomized in high (HBW and HMGI) and low (LBW and LMGI) according to the best cutoff found with receiver-operating characteristic curves.

RESULTS

Thirty-four newborns with CDH, treated with a standardized protocol, were studied. The main characteristics of the 34 patients were BW, 2886 g (1500-3620 g); gestational age, 37.7 weeks (32-42 weeks); male/female, 22/12; right/left, 8/26; prenatal diagnosis, 29; MGI, 1.31 (0.9-1.85). Only BW and MGI were significantly (P < .05) associated with mortality at the univariate analysis. The best cutoff values were 2755 g for BW (sensitivity, 70%; specificity, 74%) and 1.25 for MGI (sensitivity, 73%; specificity, 78%). Using these limits, BW and MGI resulted independently associated with mortality in the multivariate analysis. Using the 4 possible combinations, the LBW associated with the LMGI presented the highest prediction of mortality (80%).

CONCLUSIONS

Birth weight and MGI, variously combined, were predictive of mortality. Because they are not influenced by subsequent modalities of care, they can be considered as valid early severity scores in CDH and used for comparing strategies and/or performances of different centers.