Health-related quality of life in patients with paediatric inflammatory bowel disease: IMPACT-III validation in Germany.

BACKGROUND

Health related quality of life (HRQoL) in paediatric patients with inflammatory bowel disease (IBD) is typically measured using the patient reported outcome measure IMPACT-III. This measure has not yet been validated for German patients using the new 4-domain structure. As Germany has a comparatively high prevalence of paediatric IBD and as the IMPACT-III is the main HRQoL outcome measure in use, a validation in the German population is overdue.

OBJECTIVE

To validate the main patient reported outcome measure of health-related quality of life (HRQoL) in paediatric patients with inflammatory bowel disease (IBD) IMPACT-III in a German patient sample.

METHODS

Clinical and HRQoL data was gathered in the CEDATA-GPGE registry. To determine the psychometric performance of the IMPACT-III in a German sample, distribution properties, reliability (Cronbach's alpha) and validity (correlations with clinical values; known-groups validity by age, sex, and self-rated health) were calculated. In addition, a confirmatory factor analysis was performed to determine the appropriateness of the factor structure.

RESULTS

The IMPACT-III was filled out by 221 patients (Female 46%; Mage=14.05; Morbus Crohn n = 126; Ulcerative Colitis n = 79; unclassified IBD n = 18). The total score ranged from 19.29 to 95.00, without the occurrence of ceiling or floor effects. Internal consistency using Cronbach's alpha was excellent (α = 0.91) for the total scale. The total score correlated strongly with the subscales of wellbeing (r = 0.90) and social functioning (r = 0.80). Concerning validity, the subscale of wellbeing correlated with self-reported health and clinical assessments. Younger patients (< 14) reported a significantly better HRQoL than older patients (14-17). The 4-domain structure of IMPACT-III could not be confirmed through factor analysis.

CONCLUSIONS

The German version of the IMPACT-III is a valid and reliable instrument to measure HRQoL in paediatric patients with IBD. The subscales of well-being and social functioning explain most of the total score. To interpret the subdomains of the IMPACT-III further research in a longitudinal design needs to be done, especially with age-related phrasing of the items.

TRIAL REGISTRATION: German Clinical Trials Register DRKS00015505. Registered on 22.01.2019 Inclusion of patients 01.03.2019; https://drks.de/search/en/trial/DRKS00015505 .