Acid-related oesophageal sensitivity, not dysmotility, differentiates subgroups of patients with non-erosive reflux disease

Background Patients with non-erosive reflux disease can experience reflux symptoms with similar frequency and severity as those with erosive reflux disease. Oesophageal motility and acid sensitivity are thought to influence symptom occurrence. Aim To compare the effect of infused hydrochloric acid on oesophageal physiology in patients with non-erosive reflux disease and erosive reflux disease. Methods Twelve healthy controls and 39 patients with reflux disease [14 erosive reflux disease, 11 non-erosive reflux disease with normal (functional heartburn) and 14 non-erosive reflux disease with excess acid exposure] had hydrochloric acid and saline infused into distal and then proximal oesophagus. Oesophageal contraction amplitude, lower oesophageal sphincter pressure and pain intensity were documented at baseline and during each infusion. Results Patients with non-erosive reflux disease had higher pain sensitivity to acid than those with erosive reflux disease and controls. Proximal acid infusion caused greater pain than distal in patients with non-erosive reflux disease. Acid and saline sensitivity were more pronounced in patients with functional heartburn. Lower oesophageal sphincter pressure and oesophageal contraction amplitudes were lower in the erosive reflux disease and non-erosive reflux disease groups, but did not change during infusions. Conclusions Patients with non-erosive reflux disease and, to a lesser extent, patients with erosive reflux disease, are sensitive to acid in the oesophagus, being more sensitive to proximal acid. Hypersensitivity is most marked in functional heartburn patients. This acid sensitivity is not associated with motility change.