A comparison of the discriminatory power of the Inflammatory Bowel Disease Questionnaire and the SF-36 in people with ulcerative colitis

The aim of this study was to compare the discriminatory power of a generic and a condition-specific quality of life measure (the Medical Outcomes Study Short-Form 36 (SF-36) and the Inflammatory Bowel Disease Questionnaire (IBDQ)) with respect to sub-groups defined by disease-related and other factors, in a sample of patients with ulcerative colitis. Disease activity was generally more highly correlated with IBDQ scores than with SF-36 scores. The only significant differences with respect to disease extent were in the SF-36 energy/vitality and social function domains. Age was negatively and weakly to moderately correlated with the physical domains of the SF-36 but positively though weakly correlated with scores on the IBDQ emotional domain and those domains of the SF-36 related to mental well-being. Co-existing chronic illness, even on controlling for age, was associated with significantly poorer scores on the generic measure, but had little influence on IBDQ scores. In conclusion, generic and disease-specific measures of quality of life appear to be complementary rather than interchangeable. We recommend the use of both types of measure in parallel.