The Development of a Validated Instrument to Evaluate Bowel Function After Sphincter-Preserving Surgery for Rectal Cancer

Abstract

PURPOSE: Sphincter-preserving surgery is technically feasible for many rectal cancers, but functional results are not well understood. Therefore, the purpose of this study was to develop an instrument to evaluate bowel function after sphincter-preserving surgery. METHODS: A 41-item bowel function survey was developed from a literature review, expert opinions, and 59 patient interviews. An additional 184 patients who underwent sphincter-preserving surgery between 1997 and 2001 were asked to complete the survey and quality-of-life instruments (Fecal Incontinence Quality of Life, European Organization for Research and Treatment of Cancer QLQ 30/Colorectal Cancer 38). A factor analysis of variance was performed. Test-retest reliability was evaluated, with 20 patients completing two surveys within a mean of 11 days. Validity testing was done with clinical variables (gender, age, radiation, length of time from surgery), surgical variables (procedure: local excision, low anterior resection, coloanal anastomosis), reconstruction (J-pouch, straight), anastomosis (handsewn, stapled), and quality-of-life instruments. RESULTS: The survey response rate was 70.1 percent (129/184). Among the 127 patients with usable data, 67 percent were male, the median age was 64 (range, 38-87) years, and the mean time for restoration of bowel continuity after sphincter-preserving surgery was 22.9 months. Patients had a median of 3.5 stools/day (range, 0-30), and 37 percent were dissatisfied with their bowel function. Patients experienced a median of 22 symptoms (range, 7-32), with 27 percent reported as severe, 37 percent as moderate, and 36 percent as mild. The five most common symptoms were incomplete evacuation (96.8 percent), clustering (94.4 percent), food affecting frequency (93.2 percent), unformed stool (92.8 percent), and gas incontinence (91.8 percent). The factor analysis identified 14 items that collapsed into three subscales: FREQUENCY (alpha = 0.75), DIETARY (alpha = 0.78), and SOILAGE (alpha = 0.79), with acceptable test-retest reliability for the three subscales and total score (0.62-0.87). The instrument detected differences between patients with preoperative radiation (n = 67) vs. postoperative radiation (n = 15) vs. no radiation (n = 45) (P = 0.02); local excision (n = 10) vs. low anterior resection (n = 55) vs. coloanal anastomosis (n = 62) (P = 0.002); and handsewn (n = 18) vs. stapled anastomosis (n = 99) (P = 0.006). The total score correlated with 4 of 4 Fecal Incontinence Quality of Life (P < 0.01) and 9 of 17 European Organization for Research and Treatment of Cancer subscales (all P < 0.01). CONCLUSIONS: Patients undergoing sphincter-preserving surgery for rectal cancer have impaired bowel function, and those treated with radiation, coloanal anastomoses, or handsewn anastomoses have significantly worse function. This reliable and valid instrument should be used to prospectively evaluate bowel function after sphincter-preserving surgery in patients undergoing rectal cancer therapy.