Objective: Gastro-esophageal reflux (GER) is an important etiological factor inducing chronic cough. This study aims to identify the clinical features for the diagnosis of GER induced cough (GERC).
Methods: A modified Irwin's diagnostic protocol and continuous 24-hour esophageal pH monitoring were performed in 50 patients with chronic cough. Twenty patients were diagnosed as having GERC. The clinical features were compared with those of non-GER (NGER) induced cough.
Results: One hundred and ninety-two patients met the chronic cough criteria and were fully evaluated. The x +/- s of age was (40.6 +/- 12.1) years (range, 10 - 69 years) and 101 were males and 91 were females, with a cough history of 25 months (range, 2 - 487 months). GER accounted for 10.4% (n = 20) of the causes and was the fourth common cause of chronic cough. The mean +/- SD of age was (37.7 +/- 13.9) years (range, 10 - 60 years) in the GERC group, with a cough history of 61 months (range, 3 - 360 months). Cough associated with having meals (occurring while eating or anytime during the subsequent 2 h) was present in 13 out of the 20 patients in GERC, significantly higher than that in NGER (2 out of 23 patients) (chi2= 14.29, P < 0.01). The specificity, the positive predictive value and the sensitivity of cough associated with meals for GERC were 91.3%, 86.7% and 65.0%, respectively. Regurgitation associated symptom was present in 11 out of the 20 patients in the GERC group, not significantly different from that in the NGER group (8 out of 23 patients). Continuous 24 hour ambulatory esophageal pH measurement showed that reflux events were more common in upright [8.9 (range, 1.9 - 71.9)%] than in supine position [1.4 (range, 0 - 41.2)%] as well as at post-meal [20.2 (range, 2.1 - 84.2)%] than during meal period [1.95 (range, 0 - 51.6)%] (P < 0.01 and P < 0.05).
Conclusion: Cough associated with having meals is of diagnostic value for GERC. The reflux events are more frequent when patients are awake, with upright position and after meals.