We read with great interest the article by Sifrim and colleagues (Gut 2005;54:449–54) addressing the issue of the importance of weakly acidic reflux (as measured by 24 hour ambulatory pressure and pH impedance monitoring) in patients with chronic cough. The presence of asthma, postnasal drip, or use of angiotensin converting enzyme inhibitors was ruled out so that an association with gastro-oesophageal reflux was probable. They found that only 15% of cough bursts were preceded by reflux episodes, which in 4% of cases were weakly acidic and therefore not detectable by conventional automated analysis of oesophageal pH tracings. Although the temporal relationship between acid or weakly acidic reflux and cough was highly significant, it could not be demonstrated in most episodes. In this respect their findings are in agreement with a previous study by Laukka and colleagues,¹ who also used manometry for a more accurate timing of cough. Taken together, the results of the two studies suggest that the pathogenetic mechanisms usually proposed as a link between reflux and cough (micro/macroaspiration of refluxate into the airways and vagally mediated cough reflex) may be involved, at best, in a minority of cough episodes.

A different explanation has therefore to be formulated, not requiring a …