Objective: To develop a disease-specific QOL instrument (QOLRAD) addressing patient concerns in gastroesophageal reflux disease (GERD) and dyspepsia. Patients. 759 male (45%) and female (55%) patients with a mean age of 48.4 years (sd 15.2) were used in the psychometric evaluation.
Main outcome measures: A pilot version of QOLRAD, the Gastrointestinal Symptoms Rating Scale (GSRS) and the SF-36 were completed prior to endoscopy. Items with a high ceiling effect, items measuring a different construct, i.e. with a low squared multiple correlation (R < 0.5) with the other items, items that showed redundancy by a high correlation (>0.80) with another item were removed. A confirmatory factor analysis was also performed.
Results: The final questionnaire included 25 items depicting problems with emotions, vitality, sleep, eating/drinking, and physical/social functioning. The internal consistency reliability was high (alpha value overall 0.97, dimensions 0.89-94). Construct validity, i.e. the associations between similar constructs in the QOLRAD, the SF-36 and the GSRS scores was confirmed. Pain and symptom severity were markers of impaired QOL. The impact on health-related QOL was similar across the functional gastrointestinal disorders with the exception of patients with a normal endoscopy, who did slightly worse.
Conclusion: The QOLRAD is a short and user-friendly instrument with excellent psychometric properties. Its responsiveness to change in (AVMC1) clinical trials is currently being explored.