DEVELOPMENT FOR AND RESULTS OF THE USE OF A GASTROESOPHAGEAL REFLUX DISEASE-ACTIVITY INDEX AS AN OUTCOME VARIABLE IN A CLINICAL-TRIAL

Due to the significant expense of obtaining frequent endoscopy and pH monitoring measures as outcome variables available for use in a multih ospital clinical trial of gastroesophageal reflux disease, and the lac k of a suitable inexpensive index of disease activity, evaluated for b oth reliability and validity, the study planning committee decided to develop an index of gastroesophageal reflux disease activity in a pilo t study-to precede the clinical trial. In particular, the purpose of t he pilot study was to find a reliable, valid, and inexpensive index of gastroesophageal reflux disease which could be obtained independently of the treating physician and used as an outcome variable in the clin ical trial. This paper describes the pilot study and the statistical m ethodology used to derive and evaluate a gastroesophageal reflux disea se activity index model. In addition, the results of the activity inde x's use in the subsequent clinical trial's longitudinal analyses are p resented. Comparisons with the more expensive, and thus less frequentl y obtained, endoscopy and pH monitoring outcome variables are describe d.