Development and validation of a modified fecal incontinence quality of life scale for Japanese patients after intersphincteric resection for very low rectal cancer

Purpose Fecal incontinence is a frequently observed symptom after lower rectal surgery with sphincter manipulation. The aim of this study was to evaluate a proposed modification to the fecal incontinence quality of life (FIQL) scale for the assessment of the quality of life among patients with very low rectal cancer who have undergone intersphincteric resection. Methods A single 14-item composite scale was prepared that was derived from items in the "Lifestyle" and "Coping" subscales of the original FIQL. The scale was tested with a convenience sample of 152 postoperative patients. In addition to classic psychometric evaluation, newer statistical techniques, such as a multiple correspondence analysis and partial credit model, were performed to evaluate the item response patterns. Results The proposed scale exhibited an item-rest correlation of 0.66-0.84 and a Cronbach's alpha of 0.96, and was correlated with concurrently measured Social Functioning subscale of the Medical Outcomes Study Short Form 36 (-0.70), physical role limitation (-0.61), and Wexner continence grading scale (-0.61). Multiple correspondence analysis supported a uni-dimensional construct, and the partial credit model showed a varying yet overlapping range of item response thresholds across items. Several items, such as "Locating bathroom whenever going out", reflected more a serious condition than items such as "Avoiding eating-out." Weighted item scores based on estimated thresholds provided results comparable with those based on non-weighted scores. Conclusions The proposed modification to the FIQL scale exhibited high internal consistency and satisfactory concurrent and convergence validity. The modified scale is practical to administer and is sensitive to a range of functional problems associated with fecal incontinence among patients who have undergone intersphincteric resection.