Validation of the intestinal part of the prostate cancer questionnaire ”QUFW94”: psychometric properties, responsiveness, and content validity
Reidunsdatter RJ, Lund JA, Fransson P, Widmark A, Fosså SD, Kaasa S
Int J Radiat Oncol Biol Phys. 2010
Several treatment options are available for patients with prostate cancer. Applicable and valid self-assessment instruments for assessing health-related quality of life (HRQOL) are of paramount importance. The aim of this study was to explore the validity and responsiveness of the intestinal part of the prostate cancer-specific questionnaire QUFW94.
METHODS AND MATERIALS
The content of the intestinal part of QUFW94 was examined by evaluation of experienced clinicians and reviewing the literature. The psychometric properties and responsiveness were assessed by analyzing HRQOL data from the randomized study Scandinavian Prostate Cancer Group 7 (SPCG)/Swedish Association for Urological Oncology 3 (SFUO). Subscales were constructed by means of exploratory factor analyses. Internal consistency was assessed by Cronbach’s alpha. Responsiveness was investigated by comparing baseline scores with the 4-year posttreatment follow-up.
The content validity was found acceptable, but some amendments were proposed. The factor analyses revealed two symptom scales. The first scale comprised five items regarding general stool problems, frequency, incontinence, need to plan toilet visits, and daily activity. Cronbach’s alpha at 0.83 indicated acceptable homogeneity. The second scale was less consistent with a Cronbach’s alpha at 0.55. The overall responsiveness was found to be very satisfactory.
Two scales were identified in the bowel dimension of the QUFW94; the first one had good internal consistency. The responsiveness was excellent, and some modifications are suggested to strengthen the content validity.