W1832 Improved Reflux-Symptom Association Analysis to Predict PPI Treatment Outcome in Patients with Chronic Cough

Abstract

Background: Patients with unexplained chronic cough are often treated empirically with PPI, based on clinical suspicion of increased acid GER. The success rate of such approach is only 50-60%, probably due to poor patient selection. Furthermore, the predictive value of standard esophageal pHmetry for PPI treatment outcome is low. Analysis of the temporal association reflux-cough might be more relevant. However the predictive value of the Symptom Index (SI) and Symptom Association Probability (SAP) is still uncertain because a) were developed for acid reflux, heartburn and chest pain, b) consider a reflux-related cough when the patient presses an event marker within a time window of 5 or 2 min respectively, c) do not consider non-acid reflux and d) are not based on objective cough detection. We aimed to improve the assessment of reflux-cough association in order to better predict PPI treatment outcome in patients with chronic cough. Methods: 31 patients with chronic unexplained cough [19 men, age 50.5(18-71)] underwent 24h impedance-pH monitoring “off” PPI. Cough was recorded using a) by the patient (event marker) and b) objectively (pressure pattern in simultaneous gastro-esophageal manometry). After reflux monitoring patients received PPI treatment (20mg OME BID) for 8 weeks. Positive response to PPI was defined as ≥50% cough improvement. Symptom association analysis was performed considering acid or all reflux (acid+non-acid), using either the event marker or objective cough detection and SI and SAP were calculated using different time windows (0.5-6min). Results: 14/31 patients were classified as responders to the PPI. 8/14 responders and 6/17 non-responders had cough + typical GER symptoms. 9/14 responders and 4/17 non-responders had increased esophageal acid exposure (p< 0.02). The number of acid reflux events was higher in responders [34(21-58) vs. 14(8-35), p<0.05]. The best symptom association analysis was obtained using all reflux (acid+non acid), objective cough detection and a 4 min time window. Conclusion: Combined ambulatory impedance-pH-manometry allows better selection of patients with unexplained chronic cough for PPI treatment. Patients are less likely to respond to PPI if they have a negative SAP for total reflux (acid + non-acid), using a 4 minutes time window and an objective technique for cough recording.