Chronic cough and gastro-oesophageal reflux.

In their in-depth review of chronic cough and gastro-oesophageal reflux (GOR), Fontana and Pistolesi suggest that proton pump inhibitors are the most effective treatment for GOR related cough. However, most studies evaluating the efficacy of proton pump inhibitors are not placebo controlled and do not use objective markers of cough severity to assess treatment responses. We are aware of two double blind, randomised, placebo controlled trials of proton pump inhibitors, the results of which are summarised in table 1. 3 These studies show no clear benefit of proton pump inhibitors in patients with chronic cough and GOR and are consistent with the negative findings of a randomised placebo controlled study of ranitidine in a similar patient population. In our experience, only a small proportion of patients with chronic cough have a sustained improvement with proton pump inhibitors. Others have shown that there are no clear clinical indicators or findings on investigation that predict a treatment response. Further randomised controlled trials of proton pump inhibitors are required using both objective and subjective markers of cough severity such as quality of life questionnaires, cough monitors, and cough reflex sensitivity before we can accept that GOR is an important cause of chronic cough. In many ways the current data in chronic cough are consistent with findings in asthma, with good evidence of a higher than expected incidence of oesophageal dysfunction and GOR 9 but little high quality evidence of a causal association between GOR and airway symptoms or dysfunction. The interesting question is why oesophageal dysfunction occurs so commonly in patients with a diverse range of airway diseases. One possibility is that this is a manifestation of a global abnormality of upper aerodigestive reflexes, perhaps due to inflammation and dysfunction of embryologically related structures. Further studies are required to investigate this possibility.