Lactate levels as predictors of hospitalization in infants with acute bronchiolitis: a multicenter retrospective study

Background: Acute bronchiolitis (AB) is a common lower respiratory tract disease in infants and a major cause of emergency department visits and hospitalizations. Reliable biomarkers to predict hospitalization are needed because clear prognostic criteria are lacking. This study aimed to evaluate the predictive value of lactate levels for hospitalization in infants with AB. Methods: This retrospective observational study was conducted across three emergency medical centers in Korea from January 2020 to December 2022. A total of 234 infants diagnosed with AB were included. Demographic characteristics, vital signs, and laboratory results, including lactate levels, were collected and compared between discharged and hospitalized patients. Multivariable logistic regression and receiver operating characteristic (ROC) curve analyses were performed to identify significant predictors of hospitalization. Results: Lactate levels were significantly higher in the hospitalized group compared with the discharged group (2.00 vs. 1.70 mmol/L, p = 0.003). In multivariable analysis, lactate was identified as an independent predictor of hospitalization (odds ratio 1.718; 95% confidence interval 1.059–2.787). The ROC curve for lactate demonstrated an area under the curve of 0.628, indicating limited discriminative ability. Conclusions: Elevated lactate levels are associated with hospitalization in infants with AB; however, their predictive performance is modest. Larger, prospective studies are required to validate the clinical utility of lactate as a biomarker for risk stratification and decision-making in AB patients.