Esophageal 24-Hour Multichannel Intraluminal Impedance-pH Monitoring Characteristics in Children with Gastrointestinal, Respiratory, or Chest Symptoms: A Single-Center Retrospective Cross-Sectional Study

Background: Children referred for assessment of suspected gastroesophageal reflux disease (GERD) may present predominantly with gastrointestinal, respiratory, or chest symptoms. This study compared multichannel intraluminal impedance-pH (MII-pH) reflux characteristics across these presenting-symptom groups. Methods: This single-center retrospective cross-sectional study included 202 children monitored between September 2024 and June 2026. The principal comparison included 157 children aged ≥1 year: 32 with gastrointestinal, 86 with respiratory, and 39 with chest symptoms. Forty-one infants were analyzed separately. Group comparisons used nonparametric tests, with age- and sex-adjusted median and logistic regression for continuous outcomes and abnormal monitoring classifications, respectively. Results: In the principal comparison of children aged ≥1 year, the weakly acidic reflux proportion and proximal reflux ratio did not differ between the respiratory or chest symptoms group and the gastrointestinal group. However, the proportion of abnormal classifications recorded in the original clinical reports was higher in the gastrointestinal group (84.4% vs. 32.6% vs. 38.5%, p < 0.001; adjusted odds ratios 0.064 and 0.093 for the respiratory or chest symptoms groups, respectively). In an exploratory analysis of the infant cohort, which included only seven children with gastrointestinal symptoms, the non-gastrointestinal-symptom group had a higher weakly acidic reflux proportion (83.6% vs. 62.9%, p = 0.008), whereas the absolute number of weakly acidic reflux events did not differ significantly (36.0 vs. 61.0, p = 0.093). Conclusions: Children presenting predominantly with respiratory or chest symptoms did not exhibit higher weakly acidic or proximal reflux proportions than those with gastrointestinal symptoms. Differences in abnormal report-based MII-pH classifications should be interpreted cautiously because of potential interpretation bias and should not be considered evidence of independently confirmed differences in GERD prevalence.