Association of Salivary Pepsin with Systemic Inflammatory Biomarkers and Laryngeal Disease Severity in Patients with Laryngopharyngeal Reflux–Associated Chronic Laryngitis

Abstract

Background: Laryngopharyngeal reflux (LPR) is clinically heterogeneous and symptoms and/or laryngoscopic signs alone have limited specificity. While salivary pepsin is a non-invasive measure of gastric-content exposure, its association with systemic inflammation and severity of laryngeal disease is not well described. Objectives: to assess the correlation between salivary pepsin concentration and the systemic inflammatory biomarkers in chronic laryngitis associated with LPR. Materials and Methods: This was a prospective analytical comparative case-control study involving 180 adults: 60 patients with LPR-associated chronic laryngitis, 60 patients with chronic laryngitis without objective evidence of LPR and 60 healthy controls. Three timed saliva samples were analysed for pepsin A using quantitative enzyme-linked immunosorbent assay (ELISA). High sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), complete blood count-derived indices, Reflux Symptom Score-12 (RSS-12) and Reflux Sign Assessment-10 (RSA-10) were assessed. Multivariable models and receiver operating characteristic (ROC) analyses were used. Results: Maximum salivary pepsin was highest in the LPR group (median, 84.6 ng/mL; interquartile range [IQR], 57.3–126.8), followed by non-LPR chronic laryngitis (24.8 ng/mL; IQR, 13.1–43.7) and controls (8.7 ng/mL; IQR, 4.2–17.6; p<0.001). The graded pattern was also observed for IL-6, hs-CRP, TNF-α, NLR, PLR, and SII. Pepsin correlated with IL-6 (rₛ=0.54), hs-CRP (rₛ=0.47), RSS-12 (rₛ=0.63), and RSA-10 (rₛ=0.59; all p<0.001). In the comparison with non-LPR chronic laryngitis, pepsin (adjusted odds ratio [aOR] per 10 ng/mL, 1.28; 95% confidence interval [CI], 1.14–1.44) and IL-6 (aOR per 1 pg/mL, 1.31; 95% CI, 1.09–1.58) were independently associated with LPR. The area under the ROC curve (AUC) for pepsin alone was 0.874 and the AUC for the combined biomarker-clinical model was 0.944 (internally validated). Conclusions: Quantitative salivary pepsin correlated with systemic inflammatory activation and severity of symptoms and laryngoscopy. Addition of pepsin to IL-6 and hs-CRP and clinical covariates increased discrimination between LPR-associated and non-LPR chronic laryngitis.