International validation of a health-related quality of life questionnaire in patients with erosive gastro-oesophageal reflux disease

Although erosive gastro-oesophageal reflux disease (GERD) is a highly prevalent condition, there is no specific, valid, reliable and sensitive questionnaire that allows evaluating treatment-induced changes in health-related quality of life (HRQoL). To design a self-administered questionnaire, the GERD Analyzer (GERDyzer), for use in clinical studies. The GERDyzer comprises 10 dimensions each illustrated by pictogram-like drawings, simplifying communication with the patients. Self-assessment is performed by 100 mm Visual Analogue Scales. For validation, a 5-week clinical trial involving 395 patients (per-protocol) with oesophagitis was conducted. Patients were treated with pantoprazole (40 mg o.d.) for 28 days. Psychometric analyses included internal consistency, test-retest reliability, responsiveness and construct validity. Factor analysis showed consistency of the dimensions and no reduction was necessary. Validation of GERDyzer indicated high internal consistency (Cronbach's alpha = 0.95) and test-retest reliability (intraclass correlation coefficient =0.91). Responsiveness of the total score expressed by nonparametric effect size was 1.38. Comparison of scores with other questionnaires resulted in logical correlation levels depending on the respected concepts measured. GERDyzer proved to be highly valid, reproducible and responsive. It allows reliably assessing treatment-induced changes in HRQoL in erosive GERD.