Validation of the Korean Version of the Gastroesophageal Reflux Disease Questionnaire for the Diagnosis of Gastroesophageal Reflux Disease

BACKGROUND/AIMS: The Gastroesophageal Reflux Disease Questionnaire (GerdQ) has been developed and validated as a tool for the diagnosis of gastroesophageal reflux disease (GERD) in patients with gastrointestinal symptoms. However, the GerdQ and the cutoff value for determining GERD has not been validated in Korea. METHODS: Patients with symptoms suggestive of GERD were consecutively recruited. The Korean version of GerdQ was developed through a forward-backward translation process according to the cross-cultural adaptation method. Endoscopically documented esophagitis, abnormal results on 24-hour ambulatory pH recording with symptom association monitoring, or response to proton pump inhibitor treatment were used as diagnostic references for GERD. The reproducibility and test characteristics of the Korean version of GerdQ were assessed. RESULTS: A total of 149 patients with a median age of 55 years were analyzed. The intra-class correlation coefficient of 2 subsequently measured GerdQ scores was 0.651 (95% CI, 0.518–0.748). The cutoff value of 8 was found to have the highest sensitivity (64.9%; 95% CI, 56.2–73.7) and specificity (71.4%; 95% CI, 56.5–86.4) for the diagnosis of GERD. The questionnaire had a high positive predictive value (88.1%; 95% CI, 81.2–95.0), but a low negative predictive value (38.5%; 95% CI, 26.2–50.3) for GERD. Any symptom improvement on proton pump inhibitor treatment showed a sensitivity of 93.0% (95% CI, 88.3–97.7) and a specificity of 48.6% (95% CI, 32.0–65.1) for GERD. CONCLUSION: The Korean version of GerdQ is a useful complementary tool in the diagnosis of GERD.