Designing a faecal incontinence instrument using survey data

The development of instruments for the measurement of faecal incontinence symptoms and quality of life impact is at an early stage in psychometric terms (Thomas et al., 2006). The absence of large scale studies and clinical data makes the selection of reliable and valid measures difficult. Issues surrounding the actual content of questionnaires and scoring systems are also hotly debated. Some of these issues include: What do you mean by the severity of symptoms (Flatus, Liquid, or Solid Stool)? How do you measure the frequency of symptoms? Do you include questions about the use of pads? Do you ask questions about the impact of faecal incontinence? This paper examines these content issues in detail, in order to offer some useful pointers for questionnaire revision and development in the future. Recently the Wexner Faecal Continence Grading Scale (Jorge and Wexner, 1993) and a number of other items pertaining to faecal incontinence were included in the 2004 South Australian Health Omnibus Survey (SAHOS). The performance of these faecal incontinence items in SAHOS will be used as examples to demonstrate some of the key design issues.