Pyloric index: a novel nomogram predictor of metabolic alkalosis in congenital hypertrophic pyloric stenosis.

Background: Metabolic alkalosis (MA) is a common complication of congenital hypertrophic pyloric stenosis (CHPS). This study develops and validates a nomogram to predict MA probability in CHPS infants.

Methods: A retrospective study was conducted on CHPS patients at the First Affiliated Hospital of Zhengzhou University. Patients were divided into CHPS and MA-CHPS groups. Lasso and logistic regression selected predictive factors, and a nomogram was developed. Discriminative ability was assessed using the C-index with bootstrap validation. Calibration curves evaluated predictive accuracy, while decision curve analysis (DCA) assessed clinical applicability.

Results: A total of 107 cases were included in the final analysis, with 81 in the CHPS group and 26 in the MA-CHPS group. The predictive nomogram included the following factors: weight at diagnosis, symptom duration, and pyloric index (PI). The C-index of the predictive nomogram was determined to be 0.818, with a bootstrap validation (1000 resamples) yielding a corrected C-index of 0.798, indicating good discriminative ability. Calibration curves demonstrated a high degree of consistency between predicted and actual results. DCA confirmed good clinical utility.

Conclusion: We developed a nomogram to predict the probability of MA in CHPS patients, enabling early identification of poor prognosis and improving outcomes.

Impact statement: This study presents a novel predictive model for assessing the probability of metabolic alkalosis (MA) in congenital hypertrophic pyloric stenosis (CHPS) infants. It is the first model integrating the pyloric index (PI) as a predictive factor, alongside weight at diagnosis and symptom duration. The nomogram demonstrated strong discriminative ability and clinical utility, aiding early MA identification and improving perioperative management. By providing a practical risk stratification tool, this model enhances clinical decision-making, facilitates timely interventions, and ultimately improves outcomes for CHPS infants.