Predictive Value of Digestive Enzymes in Patients With Reflux‐Induced Chronic Cough

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Objective To investigate the presence and clinical value of salivary elastase, pepsin, trypsin, cholesterol, and bile salts in the development of laryngopharyngeal reflux disease‐related chronic cough (LPRD‐CC). Study Design Prospective controlled study. Setting University hospital study. Methods Patients with LPRD at the 24‐hour hypopharyngeal‐esophageal multichannel intraluminal impedance‐pH monitoring were recruited from two European hospitals. Symptoms and findings were evaluated with the reflux symptom score (RSS), quality‐of‐life RSS (QoL‐RSS), and the reflux sign assessment (RSA) at baseline and following 3 months of treatment. Pepsin, trypsin, elastase, cholesterol, and bile acids were measured in the saliva of patients. Clinical presentation and enzyme patterns were compared between patients with LPRD‐CC versus patients without chronic cough. Predictive values of digestive enzymes on clinical patterns were assessed. Results Of the 104 recruited patients, 54 had LPRD‐CC and 50 did not. Patients with chronic cough demonstrated significantly lower pharyngeal upright reflux events but higher RSS compared to those without chronic cough. The CC group demonstrated significant reduction of RSS (164.4 ± 104.5 vs 105.1 ± 103.2) and RSA (27.7 ± 6.6 vs 21.6 ± 8.1) following treatment. RSS (78.4 ± 51.3 vs 50.2 ± 49.7) and RSA (24.8 ± 7.9 vs 21.5 ± 10.3) were similarly reduced in the non‐CC group. The chronic cough group maintained significantly higher scores in otolaryngological RSS ( P = .033), respiratory RSS ( P = .036), overall RSS ( P = .035), and RSS quality of life (RSS‐QoL) ( P = .007). Salivary elastase demonstrated moderate correlation with both chronic cough presence ( r s = 0.325) and RSS ( r s = 0.353), while salivary bile salts correlated strongly with RSS‐QoL ( r s = 0.564). In patients with chronic cough, esophageal acid exposure time showed a significant negative correlation with salivary pH ( r s = −0.443). Conclusion LPRD patients with chronic cough demonstrated higher symptom severity than those without, with salivary elastase and bile salts as potential predictors of clinical findings.