The IMPACT questionnaire: a valid measure of health-related quality of life in pediatric inflammatory bowel disease.

Background and aims: IMPACT is a disease-specific health-related quality-of-life questionnaire developed for use in pediatric inflammatory bowel disease through a process of patient interviews and analysis of patient responses to an item-reduction questionnaire. This study sought to assess the feasibility, reliability, and validity of the instrument. Methods: The readability statistics and number of unanswered questions were assessed among 147 patients (97 CD, 50 UC) with mean age 14.4 ± 2.2 years (range 9.2-18.0 years) using the self-administered questionnaire. Internal consistency was assessed with Cronbach's a and test-retest reliability using intra-class correlation coefficient (ICC). Construct validity was based on a priori hypotheses. Mean total scores were compared by ANOVA among patients grouped according to disease activity and disease severity within the past year. Results: The readability statistic showed a Flesch-Kincaid Grade level of 4.5. Only 0.68% of questions were left blank. Reliability was excellent with Cronbach's α = 0.96, and an ICC of 0.90 in patients with stable disease over a two-week period (n = 32). The mean total IMPACT score for patients with quiescent disease (180 ± 32) was significantly higher (better QOL) than for those with active disease (146 ± 31 for mild, 133 ± 34 for moderate/severe) (P < 0.005). Conclusions: The IMPACT questionnaire is a valid and reliable reflection of health-related quality of life of older children and adolescents with both ulcerative colitis and Crohn's disease.