[Study on the characteristics of laryngopharyngeal reflux events in patients with obstructive sleep apnea]

Objective: To study the characteristics of laryngopharyngeal reflux (LPR) events in patients with obstructive sleep apnea (OSA). Methods: This cross-sectional study analyzed OSA patients who were admitted in the Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of the Chinese PLA General Hospital between November 2020 to July 2023[OSA group, 52 males, 6 females, aged 23-69 (41.22±11.42) years], and non-OSA patients admitted during the same period serve as the control group[non-OSA group, 40 males, 1 female, aged 21-68 (45.12±11.30) years]. All participants completed the Reflux Symptom Index (RSI), Reflux Finding Score (RFS) scale, and 24-hour Hypopharyngeal Esophageal Multichannel Intraluminal Impedance-pH (HEMII-pH) monitoring. LPR events were categorized based on their physical composition-liquid, gas, or gas-liquid mixed, according to the change of impedance values; and further classified by pH levels as acidic, weakly acidic, or alkaline. Differences in LPR events physical properties and the time trends of LPR events between the two groups were compared. Group comparisons were performed using t-test or Mann-Whitney U-test. Analyses were conducted using Pearson, Spearman, or Kendall's tau-b correlation analysis. Categorical data were analyzed using chi-square test. Results: A total of 99 patients were enrolled, including 58 with OSA and 41 without OSA. Of these, 88.89% (88/99) met the diagnostic criteria for laryngopharyngeal reflux disease (LPRD). In LPRD patients, the median proportion of non gas reflux events and the number of alkaline reflux were significantly higher in the OSA with LPRD group than in the non OSA with LPRD group (70.00% vs 36.36%, 0 vs 0, Z-values respectively -3.373, -3.134, P<0.01). Liquid reflux proportion and the number of both liquid and mixed reflux events showed a positive correlation with the apnea-hypopnea index (AHI) (r-values respectively 0.304, 0.326, 0.268, P<0.05), while the gas reflux constituent ratio was inversely correlated with AHI (r=-0.358, P<0.01). The frequency and proportion of nocturnal reflux events showed a positive correlation with AHI (r-values respectively 0.250, 0.211, P<0.05). A significantly higher proportion of OSA with LPRD group experienced both daytime and nighttime reflux compared to non OSA with LPRD group (66.67% vs 38.71%, P<0.05). In LPRD patients, over 50% of all LPR events occurred within 3 hours after each of the three main meals. Conclusions: In OSA with LPRD patients, LPR events are predominantly non gas in nature. OSA with LPRD patients exhibits a higher proportion and frequency of nocturnal reflux events and a greater number of alkaline reflux episodes compared to non OSA with LPRD patients.