The clinical application value of salivary pepsin in the diagnosis of gastroesophageal reflux diseases.

Background: Peptest is a noninvasive and convenient diagnostic kit for gastroesophageal reflux disease (GERD). We aimed to explore the application value of Peptest in the diagnosis of GERD.

Methods: Patients suspected of GERD all completed 24 h pH-impedance monitoring (24 h MII-pH) and then took proton pump inhibitor (PPI) 2 weeks. The postprandial, post-symptom and random salivary samples were taken. Receiver operating characteristic analysis was used to identify the best cutoff value of Peptest, to differentiate GERD patients from non-GERD patients and the optimal sampling time of Peptest was analyzed. Reflux characteristics and esophageal motility between Peptest (+) group and Peptest (-) group were compared in negative 24 h MII-pH patients. Peptest concentration were compared among non-reflux, distal reflux, and proximal reflux groups according to 24 h MII-pH curve.

Results: The area under the curve of post-symptom Peptest was highest in three time points and the diagnostic specificity was 81.0% and sensitivity was 53.3% with the diagnostic value of 86 ng/mL. Compared with negative Peptest group, distal mean nocturnal baseline impedance was significantly lower, gastroesophageal junction contractile integral was substantially lower in positive Peptest group in negative 24 h MII-pH patients. The concentration of post-symptom and postprandial Peptest increased gradually in the non-reflux, distal reflux, and proximal reflux groups. Conclusions & inferences: Peptest has a relatively low diagnostic value for GERD. Post-symptom Peptset is the best sampling time with the optimal value of 86 ng/mL and may have auxiliary diagnostic value for negative 24 h MII-pH patients. Peptest may assist 24 h MII-pH in monitoring proximal reflux.