New Developments in Reflux-Associated Cough

Abstract

Gastro-oesophageal reflux disease (GORD) is generally considered one of the three main causes of chronic cough, along with asthma and nasal disease. The diagnosis of GORD is often based upon a successful trial of anti-acid treatment however GORD is a complex condition taking many forms. Only recently have studies started to address the different types of GORD in patients with chronic cough and how these may infer the mechanisms linking these common conditions. GORD can be assessed in a number of ways; whilst endoscopy provides evidence of oesophagitis (i.e. erosive disease), 24-h ambulatory oesophageal pH monitoring may demonstrate abnormal oesophageal acid exposure in the absence of oesophageal damage (i.e. non-erosive disease). The development of oesophageal impedance monitoring now allows the assessment of all reflux events (regardless of degree of acidity) and further classification of reflux by the proximal extension e.g. to upper oesophagus or even pharynx. Chronic cough patients may still be considered to have GORD if there is a significant temporal association between reflux events and coughing. Recent studies have examined the relationships between cough and reflux events, the roles of distal and proximal/pharyngeal reflux and also micro-aspiration in chronic cough patients. Increasing evidence suggests a significant proportion of patients display statistical associations between reflux and cough events, in the absence of an excessive numbers of reflux events either within or outside of the oesophagus.