Reliability and validity of a survey to measure bowel function and quality of life in long-term rectal cancer survivors.

Abstract

Examination of reliability and validity of a specialized health-related quality of life questionnaire for rectal cancer (RC) survivors (≥5 years post-diagnosis). We mailed 1,063 Kaiser Permanente (KP) RC survivors (313 ostomy and 750 anastomosis) a questionnaire containing the Modified City of Hope Quality of Life-Ostomy (mCOH-QOL-O), SF-12v2, Duke-UNC Functional Social Support Questionnaire (FSSQ), and Memorial Sloan-Kettering Cancer Center Bowel Function Index (BFI). We adapted certain BFI items for use by subjects with intestinal ostomies. We evaluated reliability for all instruments with inter-item correlations and Cronbach's alpha. We assessed construct validity only for the BFI in the ostomy group, because such use has not been reported. The overall response rate was 60.5 % (577 respondents/953 eligible). Compared with non-responders, participants were on average 2 years younger and more likely non-Hispanic white, resided in educationally non-deprived areas, and had KP membership through a group. The mCOH-QOL-O, SF-12, and FSSQ were found to be highly reliable for RC survivors. In the ostomy group, BFI Urgency/Soilage and Dietary subscales were found to be reliable, but Frequency was not. Factor analysis supported the construct of Urgency/Soilage and Dietary subscales in the ostomy group, although one item had a moderate correlation with all three factors. The BFI also demonstrated good concurrent validity with other instruments in the ostomy group. With possible exception of the BFI Frequency subscale in populations with ostomies, components of our survey can be used for the entire population of RC survivors, no matter whether they received anastomosis or ostomy.