H. Hjortswang et al., Validation of the inflammatory bowel disease questionnaire in Swedish patients with ulcerative colitis, SC J GASTR, 36(1), 2001, pp. 77-85
Background: The Inflammatory Bowel Disease Questionnaire (IBDQ) is a diseas
e-specific health-related quality of Life (HRQOL) questionnaire including f
our dimensions and a sum score. The aim of this study was to assess the int
ernal and external validity, reliability, and sensitivity of a Swedish vers
ion of the IBDQ. Methods: Three hundred consecutive patients with ulcerativ
e colitis completed the IBDQ and three other health-related quality of life
questionnaires (the Rating Form of IBD Patient Concerns (RFIPC), the Shea
Form-36 (SF-36) and the Psychological General Well-Being (PGWB) index). Dis
ease activity was evaluated using a 1-week symptom diary, blood tests and r
igid sigmoidoscopy. One hundred and fourteen patients filled in the questio
nnaire a second time, of whom 75 had been in stable remission for over 6 mo
nths and 39 had a significant clinical change in disease activity. Results:
Factor analysis of the 32 IBDQ items did not support the four dimensional
scores. The dimensional scores had sufficient convergent validity, but low
discriminative validity and homogeneity. The homogeneity was also low for t
he sum score. The inter-dimensional correlations were high. The concurrent
validity was supported by correlations between the dimensional scores and o
ther measures of disease activity and HRQOL. Patients in relapse scored sig
nificantly less on the sum score and the four dimensions compared to patien
ts in remission. The test-retest correlations for the dimensional scores we
re 0.40-0.76. Patients with a change in disease activity during the 6-month
follow-up period had a significant change in IBDQ scores not found in thos
e who remained in remission. Conclusions: The Swedish version of the IBDQ h
ad external validity and was shown to be a reliable and sensitive measure o
f HRQOL in ulcerative colitis, though there are some concerns regarding the
internal validity. The use of a sum score was not supported and the questi
onnaire may benefit from a redivision of items into dimensions with better
homogeneity and discriminative validity.