Evidence of Association Between GERD and Asthma

The prevalence of GERD increases in asthmatics compared with normal controls. The prevalence of GERD in asthmatics is estimated at between 34% and 89%5,12-16, which probably reflects the variation in GERD definition and populations studied. Although a proportion of patients with GERD have no obvious symptoms, data showed that, among the asthmatics, 77%, 55%, and 24% experienced heartburn, regurgitation, and swallowing difficulties, respectively17. Sontag et al18 performed endoscopy and esophageal biopsy on 186 adult asthmatics, and revealed that 43% of the patients with asthma had esophagitis or Barrett’s esophagus, or both. In healthy volunteers, only 13.8% have abnormal endoscopic findings in esophagus, and 8.5% presented with erosive esophagitis19. Sontag et al5 measured lower esophageal sphincter (LES) pressure and studied gastroesophageal reflux (GER) patterns using 24-h esophageal pH monitoring in 44 controls and 104 adult asthmatics. They found that 82% of adult asthmatics had abnormal gastroesophageal reflux. Compared with the controls, asthmatics had significantly lower LES pressure, greater acid exposure time, more frequency reflux episodes, and longer clearance times in both the upright and supine positions5. Several studies have demonstrated that significant proportion of patients with asthma suffered GERD without classic GERD symptoms of heartburn or regurgitation. Harding et al13 reported that 24-h esophageal pH tests were abnormal in 29% asthmatics without reflux symptoms. Another study performed by Harding et al20 evaluated 26 patients with stable asthma without reflux symptoms using esophageal manometry and 24-h esophageal pH testing, and found that the prevalence of abnormal 24-h esophageal pH tests in asthma European Review for Medical and Pharmacological Sciences