The responsiveness and minimally important difference for the Accidental Bowel Leakage Evaluation questionnaire

Introduction and hypothesis: We describe the responsiveness and minimally important difference (MID) of the Accidental Bowel Leakage Evaluation (ABLE) questionnaire.

Methods: Women with bowel leakage completed ABLE, Patient Global Impression of Improvement, Colo-Rectal Anal Distress Inventory, and Vaizey questionnaires pretreatment and again at 24 weeks post-treatment. Change scores were correlated between questionnaires. Student's t tests compared ABLE change scores for improved versus not improved based on other measures. The MID was determined by anchor- and distribution-based approaches.

Results: In 266 women, the mean age was 63.75 (SD = 11.14) and 79% were white. Mean baseline ABLE scores were 2.32 ± 0.56 (possible range 1-5) with a reduction of 0.62 (SD = 0.79) by 24 weeks. ABLE change scores correlated with related measures change scores (r = 0.24 to 0.53) and differed between women who improved and did not improve (all p < 0.001). Standardized response means for participants who improved were large ranging from -0.89 to -1.12. Distribution-based methods suggest a MID of -0.19 based on the criterion of one SEM and -0.28 based on half a standard deviation. Anchor-based MIDs ranged from -0.10 to -0.45. We recommend a MID of -0.20.

Conclusions: The ABLE questionnaire is responsive to change, with a suggested MID of -0.20.