The diagnosis of gastro-oesophageal reflux disease (GERD) remains a challenge as both invasive methods and symptom-based strategies have limitations. The symptom-based management of GERD in primary care may be further optimised with the use of a questionnaire. To assess the diagnostic validity of the GerdQ questionnaire in patients with symptoms suggestive of GERD. Patients with symptoms suggestive of GERD without alarm features, underwent upper endoscopy, and if normal, pH-metry. Patients were followed for 4 weeks and GerdQ was completed blinded to the investigator at both visits. Reflux oesophagitis or pathological acid exposure was used as diagnostic references for GERD. The diagnostic accuracy for GERD on symptom response to proton pump inhibitor (PPI) was assessed. Among the 169 patients, a GerdQ cutoff ≥9 gave the best balance with regard to sensitivity, 66% (95% CI: 58-74), and specificity, 64% (95% CI: 41-83), for GERD. The high prevalence of reflux oesophagitis (81%) resulted in a high proportion of true positives, but at the same time a high proportion of false-negatives. Consequently, GerdQ had a high positive predictive value, 92% (95% CI: 86-97), but a low negative predictive value, 22% (95% CI: 13-34), for GERD. Symptom resolution on PPI therapy had high sensitivity, 76% (95% CI: 66-84), but low specificity, 33% (95% CI: 17-53), for GERD. GerdQ is a useful complementary tool for the diagnosis of gastro-oesophageal reflux disease in primary care. The implementation of GerdQ could reduce the need for upper endoscopy and improve resource utilisation. Symptom resolution on proton pump inhibitor did not predict gastro-oesophageal reflux disease. © 2013 Blackwell Publishing Ltd.
