Design and validation of a comprehensive fecal incontinence questionnaire.
OBJECTIVE
Fecal incontinence can have a profound effect on quality of life. Its prevalence remains uncertain because of stigma, lack of consistent definition, and dearth of validated measures. This study was designed to develop a valid clinical and epidemiologic questionnaire, building on current literature and expertise.


METHODS
Patients and experts undertook face validity testing. Construct validity, criterion validity, and test-retest reliability was undertaken. Construct validity comprised factor analysis and internal consistency of the quality of life scale. The validity of known groups was tested against 77 control subjects by using regression models. Questionnaire results were compared with a stool diary for criterion validity. Test-retest reliability was calculated from repeated questionnaire completion.


RESULTS
The questionnaire achieved good face validity. It was completed by 104 patients. The quality of life scale had four underlying traits (factor analysis) and high internal consistency (overall Cronbach alpha = 0.97). Patients and control subjects answered the questionnaire significantly differently (P < 0.01) in known-groups validity testing. Criterion validity assessment found mean differences close to zero. Median reliability for the whole questionnaire was 0.79 (range, 0.35-1).


CONCLUSIONS
This questionnaire compares favorably with other available instruments, although the interpretation of stool consistency requires further research. Its sensitivity to treatment still needs to be investigated.
Macmillan
Alexandra K
AK
School of Population Health, University of Auckland, Auckland, New Zealand. a.macmillan@auckland.ac.nz
Merrie
Arend E H
AE
Marshall
Roger J
RJ
Parry
Bryan R
BR
D000328:Adult; D005163:Factor Analysis, Statistical; D005242:Fecal Incontinence / Q000503:physiopathology / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D011594:Psychometrics; D011788:Quality of Life; D012044:Regression Analysis; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires