Reflux pattern and role of impedance-pH variables in predicting PPI response in patients with suspected GERD-related chronic cough

BACKGROUND: Gastro-oesophageal reflux disease (GERD) may contribute to the onset of chronic cough (CC); however, the multichannel intraluminal impedance-pH (MII-pH) monitoring is often within the normal range and the response to proton pump inhibitors (PPIs) unsatisfactory. The measure of impedance baseline (IB) increases the sensitivity of MII-pH in patients with typical symptoms. AIM: To evaluate the role of MII-pH variables, including IB, in predicting PPI response and to define the characteristics of the reflux pattern in CC patients. METHODS: Prospectively selected CC patients suspected GERD-related underwent MII-pH monitoring and, therefore, received a double dose of PPIs for at least 6 weeks. Patients filled symptom scores before MII-pH and after PPI therapy. MII-pH data were compared with those obtained in 60 non-erosive reflux disease patients with typical symptoms. RESULTS: A total of 156 CC patients entered the study: 68 (43.5%) responders and 88 (56.5%) nonresponders to PPIs. The number of reflux episodes was significantly higher in CC compared with that in typical symptoms patients. Nonresponder CC patients with a pathological acid exposure time (AET) and/or IB value were 43/88 (49%), while 15/88 (17%) presented only pathological AET (P < 0.001). CC patients with a pathological AET or IB, or with both a pathological AET and IB, showed a probability of PPI response twofold greater than patients with normal AET and IB. CONCLUSIONS: The presence of a pathological AET or pathological IB in CC patients is associated with a greater probability of PPI response. IB is a promising variable in patients with CC, as it increases the diagnostic yield of MII-pH and allows confirmation of the GERD diagnosis in these patients.