Background: The GerdQ scoring system may be a useful tool for managing gastro-oesophageal reflux disease. However, GerdQ has not been fully validated in Asian countries. Objective: To validate the Japanese version of GerdQ and to compare this version to the Carlsson-Dent questionnaire (CDQ) in both general and hospital-based populations. Methods: The questionnaires, including the Japanese versions of GerdQ and CDQ, and questions designed to collect demographic information, were sent to a general population via the web, and to a hospital-based population via conven tional mail. The optimal cutoff GerdQ score and the differences in the characteristics between GerdQ and CDQ were assessed. Results: The answers from 863 web-responders and 303 conventional-mail responders were analysed. When a GerdQ cutoff score was set at 8, GerdQ significantly predicted the presence of reflux oesophagitis. Although the GerdQ scores were correlated with the CDQ scores, the concordance rates were poor. Multivariate analysis results indicated that, the additionaluse of over-the-counter medications was associated with GerdQ score≥8, but not with CDQ score≥6. Conclusions: The GerdQ cutoff score of 8 was appropriate for the Japanese population. Compared with CDQ, GerdQ was more useful for evaluating treatment efficacy and detecting patients’ unmet medical needs.
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