Early prediction of poor outcome in extremely low birth weight infants by classification tree analysis

Objective

To predict death or neurodevelopmental impairment (NDI) in extremely low birth weight infants by classification trees with recursive partitioning and automatic selection of optimal cut points of variables.

Study design

Data from the Trial of Indomethacin Prophylaxis in Preterms were randomly divided into development (n = 784) and validation sets (n = 262). Three models were developed for the combined outcome of death (8 days to 18 months) or NDI (cerebral palsy, cognitive delay, deafness, or blindness at 18 months corrected age): antenatal: antenatal data; early neonatal: antenatal + first 3 days data; and first week: antenatal, first 3 days, and 4th to 8th days data. Decision trees were tested on the validation set.

Results

Variables associated with death/NDI in each model were: Antenatal: Gestation ≤25.5 weeks and antenatal steroids <7 days. Early neonatal: Birth weight ≤787 g and fluid intake >101 mL/kg/d. First week: Birth weight ≤787 g: transfusion >3 mL/kg/d. Birth weight >787 g: cranial echodense intraparenchymal lesion and transfusion >11 mL/kg/d. Correct classification rates were 61% to 62% for all models.

Conclusions

The ability to predict long-term morbidity/death in extremely low birth weight infants does not improve significantly over the first week of life. Effects of different variables depend on age.

Abbreviations: ELBW, Extremely low birth weight, NDI, Neurodevelopmental impairment, TIPP, Trial of Indomethacin Prophylaxis in Preterms