Predictive Value of Digestive Enzymes in Patients with Reflux-Induced Chronic Cough

Introduction: To investigate the presence and clinical value of elastase, pepsin, trypsin, cholesterol, and bile salts in the development of laryngopharyngeal reflux disease related chronic cough (LPRD-CC).

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 (QOL-RSS), and the reflux sign assessment (RSA) at baseline and 3-months post-treatment. Pepsin, trypsin, elastase, cholesterol and bile acids were measured in 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 pattern were assessed.

Results: Of the 104 recruited patients, 54 patients had LPRD-CC and 50 had not. Patients with chronic cough reported significant lower pharyngeal upright reflux events but demonstrated higher RSS compared to those without chronic cough. Both groups demonstrated significant pre- to 3-month posttreatment reduction of RSS and RSA with the chronic cough group maintaining significantly higher scores in otolaryngological RSS (p=0.033), respiratory RSS (p=0.036), overall RSS (p=0.035), and RSS quality of life (RSS-QoL) (p=0.007). Salivary elastase demonstrated moderate correlation with both chronic cough presence (rs=0.325) and RSS (rs=0.353), while salivary bile salts correlated strongly with RSS-QoL (rs=0.564). In patients with chronic cough, esophageal acid exposure time showed significant negative correlation with salivary pH (rs=-0.443).

Conclusions: LPRD patients with chronic cough demonstrated higher symptom severity than those without, with salivary elastase and bile salts as potential predictors of clinical findings.