Serum KLF2, YKL-40, and vitamin A levels and their prognostic value in neonatal respiratory distress syndrome

Objective This study aimed to clarify the clinical significance of serum Krüppel-like factor 2 (KLF2), chitinase-3-like protein 1 (YKL-40), and vitamin A levels in neonatal respiratory distress syndrome (NRDS) and to determine their utility in predicting adverse outcomes. Methods This study included 120 neonates with NRDS and 60 healthy controls. NRDS cases were stratified by radiographic severity into mild, moderate, and severe subgroups, and further divided into survival and non-survival groups based on outcomes. Serum KLF2, YKL-40, and vitamin A levels were measured and compared across groups. Logistic regression analysis was used to identify factors influencing NRDS prognosis, and a nomogram model was constructed. Predictive performance was evaluated using ROC curves, calibration curves, and DCA. Results Serum KLF2 and vitamin A concentrations progressively decreased with increasing disease severity, whereas YKL-40 levels showed the opposite trend (all P < 0.05). Compared with survivors, non-survivors exhibited markedly lower KLF2 and vitamin A levels but elevated YKL-40 levels (all P < 0.05). Multivariable analysis demonstrated that KLF2, YKL-40, and vitamin A were independently associated with adverse outcomes in NRDS. These factors were used to construct a nomogram prediction model with a total score of 160 points (corresponding to a probability of 0.16–0.8). The ROC curve showed an AUC of 0.918 (95% CI: 0.863–0.973); the calibration curve indicated good discrimination and consistency; and the DCA curve verified a positive net benefit within the predictive probability threshold range of 0–0.88. Conclusion Alterations in serum KLF2, YKL-40, and vitamin A levels are closely linked to disease severity and clinical outcome in neonates with NRDS. Combined assessment of these biomarkers may offer a practical approach for early prognostic stratification and risk evaluation.