Effectiveness of proton pump inhibitor in unexplained chronic cough

Background Current guidelines recommend that patients with unexplained chronic cough undergo empirical proton pump inhibitor (PPI) treatment, but scientific evidence for this treatment is lacking. We investigated the effectiveness and appropriate dose of PPI therapy in chronic cough. Methods We included 27 patients with unexplained chronic cough after excluding subjects with positive response to postnasal drip medication. Subjects were randomized to a placebo, standard, and high dose of PPI groups with blinding. The drug or placebo was administered orally for 8 weeks, and the Leicester Cough Questionnaire (LCQ) score and visual analogue scale (VAS) scores were collected. Results The LCQ score in the PPI group significantly improved from 0 weeks (11.4 +/- 1.4) to 4 weeks (14.8 +/- 1.4) and to 8 weeks (17.1 +/- 1.4), whereas that in the placebo group did not improve from 0 weeks (13.7 +/- 1.1) to 8 weeks (11.8 +/- 1.4); the difference between the 2 groups was significant (P < 0.001). In subgroup analysis according to reflux, significant improvements in the LCQ score were observed in the PPI group regardless of reflux (P < 0.001 in the reflux group and P < 0.001 in the no reflux group, respectively; P = 0.188 between the 2 groups). In addition, improvements in LCQ and VAS scores between the standard- and high-dose PPI groups were not significantly different; however, adverse reactions were induced by only the high dose (16.7%). Conclusions The results of this pilot study support the empirical use of the standard dose of PPI for 8 weeks in patients suffering from unexplained chronic cough regardless of whether reflux is present.