Diagnostic accuracy of multichannel intraluminal impedance-pH monitoring for gastroesophageal reflux-induced chronic cough

Objectives: To elucidate the accuracy and advantages of Multichannel intraluminal impedance-pH monitoring (MII-pH) in diagnosing gastroesophageal reflux-induced chronic cough (GERC). Methods: The patients with suspected GERC were recruited and underwent MII-pH, GERC was confirmed by subsequent anti-reflux treatment despite the findings of MII-pH. Its diagnostic accuracy in identifying GERC were evaluated by receiver operating characteristic (ROC) analysis and compared with that of 24-h esophageal pH monitoring. Results: Among 158 patients completing both MII-pH and anti-reflux therapy, GERC was diagnosed in 136 patients, including acid GERC in 96 patients (70.6%), non-acid GERC in 30 patients (22.0%), neither one of both GERC in 10 patients (7.4%). For the identification of GERC, MII-pH presented with the sensitivity of 92.6%, specificity of 63.6%, positive predictive value of 94.0%, negative predictive value of 58.3% and area under ROC curve of 0.863, which was totally superior to 24-h esophageal pH monitoring. As the essential criteria of MII-pH, esophageal acid exposure time and symptom associated probability had a limited diagnostic value when used alone, but improved greatly the diagnostic yield when used in combination, even with a suboptimal efficacy. Conclusion: MII-pH is a more sensitive test for identifying GERC, but with a suboptimal diagnostic efficacy.