Acid gastroesophageal reflux commonly causes chronic cough, and response to acid suppression therapy generally is lower than it is in patients with heartburn. Improvement after antireflux surgery suggests involvement of a nonacidic gastric component in the refluxate. As reported in the April 2005 issue of Gut, in a study involving 28 patients who were evaluated using 24-hour ambulatory pressure-pH-impedance monitoring, Daniel Sifrim, MD, PhD, and colleagues investigated whether chronic cough is associated with weakly acidic reflux. Manometry for precise recognition of cough and impedance-pHmetry were used to detect acidic (pH <4), weakly acidic (pH 4-7), and weakly alkaline (pH ≥7) reflux.

Most coughs (69.4%) were considered independent of reflux, and 31% occurred within 2 minutes of a reflux episode; 49% of these were reflux-cough sequences involving acidic (65%), weakly acidic (29%), and weakly alkaline (6%) reflux. Positive symptom association probability between reflux and cough was observed in 10 patients (45%; 5 acidic, 2 acidic and weakly acidic, 3 weakly acidic). This methodology allowed for the precise determination of temporal associations between cough and gastroesophageal reflux and identified a subgroup of patients who had chronic cough associated with weakly acidic gastroesophageal reflux.