Comparison of gastroesophageal reflux disease questionnaire and multichannel intraluminal impedance pH monitoring in identifying patients with chronic cough responsive to antireflux therapy.

BACKGROUND: Empirical therapy has been recommended as an initial clinical approach for treating gastroesophageal reflux-induced chronic cough (GERC). This study compared the predictive accuracy of the Gastroesophageal Reflux Disease Questionnaire (GerdQ) with the accuracy of multichannel intraluminal impedance pH monitoring (MII-pH) for GERC.

METHODS: A total of 126 consecutive patients with potential GERC were recruited to undergo MII-pH and complete the GerdQ. A final diagnosis of GERC was made after favorable response to consequent medicinal antireflux therapy, regardless of laboratory findings. The predictive accuracy of the GerdQ for GERC was assessed and compared with that of MII-pH.

RESULTS: GERC was confirmed in 102 of 126 patients (81.0%); cough was due to acid reflux in 55 (53.9%) and nonacid reflux in 47 (46.1%). The optimal cutoff point of the GerdQ for predicting GERC was defined as 8.0 according to the highest Youden index of 0.584, with a sensitivity of 66.7%, specificity of 91.7%, positive predictive value of 97.1%, and negative predictive value of 42.9%. A subanalysis for only acid GERC showed further improvement in the predictive accuracy of the GerdQ, corresponding to a sensitivity of 90.9%, specificity of 78.6%, positive predictive value of 71.4%, and negative predictive value of 96.4%. However, a meaningful GerdQ cutoff point for prediction of nonacid GERC could not be determined. In general, MII-pH was superior to the GerdQ for predicting GERC and acid GERC.

CONCLUSIONS: The GerdQ can be used for predicting acid GERC but not nonacid GERC and is inferior to MII-pH.

TRIAL REGISTRY: Chinese Clinical Trial Registry; No.: ChiCTR-ODT-12001899; URL: www.chictr.org.