ALB and Patent ductus arteriosus: The identification of the final model was carried out in the feature dimensionality reduction process of the Catboost model, and 14 risk factors were finally screened to construct the Catboost final model, including birth weight, gestational age, frequent sleep apnea, type II respiratory failure, use of drugs to close PDA, NRDS, sepsis, vasoactive drugs, WBC < 5 × 109/L, hemoglobin, serum albumin, PH < 7.25, base excess, intestinal wall thickening, and portal vein gas.