Spanish version of the ICIQ-Bowel questionnaire among colorectal cancer patients: construct and criterion validity : Comprehensive assessment of bowel function.

PURPOSE: Bowel complaints are very common among patients with colorectal cancer. However, the most used questionnaires for colorectal cancer survivors do not comprehensively comprise bowel symptoms. This study aimed to examine construct and criterion validity, as well as internal consistency, of the Chilean Version of the International Consultation on Incontinence Questionnaire Bowel Module (ICIQ-B) among people with colorectal cancer. METHODS: Cross-sectional, validation study performed with 106 colorectal cancer patients from Hospital del Salvador, Chile. Bowel function was assessed with the ICIQ-B. Construct validity was assessed with confirmatory factor analysis and hypothesis testing. Specific items of a quality-of-life questionnaire (EORTC QLQ-CR29) were used to correlate with similar ICIQ-B items for criterion validity. For internal consistency, Cronbach's alpha was computed. RESULTS: For construct validity, the confirmatory factor analysis showed that the three factors model did not fit our data. Meanwhile, hypothesis testing favored the construct validity of the instrument, considering that rectal cancer patients showed worse bowel pattern (p = 0.001), bowel control (p = 0.001) and quality of life (p < 0.001) scores compared to colon cancer patients. In addition, those patients assessed before surgery also presented worse scores bowel control (p = 0.023) and quality of life (p = 0.009) compared to post-surgical patients. Regarding criterion validity, the ICIQ-B items showed a significant correlation with similar QLQ-CR29 items. The internal reliability of the instrument was good (Cronbach's α = 0.909). CONCLUSION: Considering that this questionnaire appraises bowel function in more depth, it is recommended for use in clinical practice and research with colorectal cancer patients.