IMPACT‐III is a valid and reliable questionnaire for assessing health‐related quality of life in Swedish children with inflammatory bowel disease

Abstract

This study examined the reliability, validity and factor structure of the Swedish version of the IMPACT-III questionnaire for assessing health-related quality of life in children with inflammatory bowel disease. We recruited 202 participants aged eight to 18years, who were enrolled from 16 of the 23 paediatric gastroenterology clinics across Sweden during 2010-2013. This cross-sectional study compared two versions of the IMPACT-III questionnaire - one with six factors and 35 items and one with four factors and 19 items - plus the Paediatric Quality of Life Inventory 4.0 Generic Core Scale. Disease activity was assessed and defined as active or inactive. The mean total score for the six-factor IMPACT-III scale was 143.7/175, with a standard deviation (SD) of 17.9. There was a significant difference in mean total scores between the 133 children with inactive disease (147.8, SD: 14.9) and the 52 with active disease (133.0, SD: 20.3). Confirmatory factor analysis showed that the four-factor scale was more robust than the original six-factor scale. Concurrent validity and discriminant validity were high for both versions. The Swedish version of the IMPACT-III questionnaire was valid and reliable, but the shorter, four-factor version is quicker and may be more convenient in clinical settings.