Introduction and hypothesis: St Mark's incontinence score (SMIS) and the Wexner score have been constructed and validated as interview-based scoring systems. We developed a single questionnaire from which a separate SMIS or Wexner score could be derived. This study aimed to demonstrate the level of agreement between self-administered (sSMIS and sWexner) and interview-based (iSMIS and iWexner) scores using this questionnaire.
Methods: One hundred five consecutive patients (30 male) seen in the incontinence outpatient clinics at the Østfold Hospital Trust, Sarpsborg, and University Hospital of North Norway, Tromsø, completed the self-administered incontinence questionnaire prior to the appointment. Following clinical investigation, the patients were interviewed about their symptoms according to the SMIS and Wexner scores, with the interviewers blinded to the results from self-reported questionnaire. Agreement between total scores and between subscores of the various items were determined using interclass correlation coefficient (ICC) and kappa statistics, respectively.
Results: The self-administered questionnaire was incomplete in six cases (5.7%) and the interview-based was incomplete in two cases. Agreement was almost perfect between the iSMIS and sSMIS and between the iWexner score and sWexner score (ICC 0.90 and 0.92, respectively). Agreement was substantial to almost perfect for all items in both scoring systems, with kappa values ranging from 0.64-0.94. Mean iSMIS was 9.48 versus 9.53 for sSMIS (p = 0.90) and 8.26 versus 8.44 for the iWexner and sWexner score, respectively (p = 0.42).
Conclusion: The SMIS and Wexner scores can be completed by the patients using a single questionnaire, and the derived SMIS and Wexner scores are highly consistent with scores obtained by interview.
Keywords: Anal incontinence; Fecal incontinence; Scoring systems; St Mark’s score; Wexner score.