Validation of a quality-of-life questionnaire for patients with pituitary adenoma

Background: The purpose of this study was to develop and validate a self-administered questionnaire to measure the health-related quality of life of patients with pituitary adenoma. Methods: A patient-centred iterative process, involving a literature review and focus group interviews with 84 patients, was used to develop a preliminary 106-item questionnaire and to validate it. The final questionnaire comprised the 30 most important items chosen by 20 patients and 17 items considered important by health care professionals. For assessment of its validity and reliability, 55 patients were asked to complete the final questionnaire, RAND-36, FACT-G/FACT-Br, and Karnofsky Performance Scale (KPS). Concurrent validity of the results of our questionnaire with those of the other instruments was assessed with Pearson correlation coefficients. Known-group validity for the scores of extreme groups was assessed with a Student's t test. Test-retest reliability was determined with Pearson correlation coefficients and a Student's t test for two sets of scores obtained one month apart. Results: Forty-seven (85.5%) of the 55 questionnaires were completed. Our questionnaire was well correlated with the RAND-36, the FACT-Br, the FACT-G, and the KPS in the general health domain, but not with the KPS overall. Extreme groups (n=20) were significantly different. Test-retest reliability (n=24) was 0.88, and scores one month apart were not significantly different. Conclusion: Our patient-centred health-related quality of life questionnaire developed for patients with pituitary adenoma had good validity and reliability. This questionnaire could be used as a patient-centred outcome measure in clinical trials and for assessment of disease progression.