gms | German Medical Science

Background: In chronic illnesses, it has become typical to assess patients’ health related quality of life (HRQoL) to determine treatment efficacy. In Paediatric Inflammatory Bowel Disease (PIBD), which predominantly consists of Morbus Crohn and Ulcerative Colitis, chronic inflammations in the gastrointestinal tract lead to changing disease activity and therewith influence wellbeing. In PIBD, HRQoL is typically measured with the disease specific patient reported outcome measure (PROM) IMPACT III. It is used internationally and has shown good reliability and validity scores. A German version of the IMPACT III is available, but has only been tested in a German-French Swiss sample. As PIBD prevalence in Germany is among the highest in Europe, a validation of the only available disease specific PROM for PIBD for the German patient population is needed.

Objective: The objective of this study was to determine if the IMPACT III is a valid and reliable instrument to measure HRQoL for German PIBD patients.

Methods: The German PIBD registry CEDATA was used in a randomised controlled trial, to test the effectiveness of a registry-based feedback system for medical specialists. For this, enrolled patients filled out the IMPACT III questionnaire with their first presentation at the clinic and 12-months later. The patient registry data and HRQoL data were used for the validation.

The IMPACT III is scored from 0 (worst health) to 100 (best health), consisting of four domains (well-being, emotional functioning, body image, social functioning). 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.

Results: Data on the IMPACT III was available for N=224 patients (Morbus Crohn n=123; Ulcerative Colitis n=80; unclassified PIBD n=17) with a mean age of 14.06±2.35; and a proportion of 46.7% female patients. Mean IMPACT Score was 66.1±14.05 with no occurrence of floor or ceiling effects. Lowest self-reported health was seen in the subdomain well-being (58.3±21.8), highest in social functioning (81.4±13.0). The IMPACT III total score showed an overall Cronbach’s alpha coefficient of α=0.91. Cronbach’s alpha was lowest in the body image scale (α=0.60) and highest in the well-being scale (α=0.89).

The overall medical assessment of disease activity (rp(126) = -0.16, p=0.07) did not significantly correlate with the IMPACT III score. The respective disease activity indexes responded differently: the PCDAI index significantly correlates with the IMPACT III score (r=-0.497), but the PUCAI (r=-0.146) does not.

Known-groups validity was demonstrated by significant differences (p<0.05) on IMPACT III scores between groups of age (9-13 years: M=68.97, 14-18 years: M=63.94) and sex (female: M=63.68; male: M=68.19) as well as of self-rated wellbeing (doing well M=77.86 vs doing poorly M=56.73).

Implication for research and healthcare practice: The IMPACT III shows good reliability in a German population. The questionnaire corresponds well to patient’s self-reported wellbeing, but the findings in relation to clinical assessments are inconclusive. Calculating the responsiveness of the questionnaire and a confirmatory factor analysis are planned.

Funding: Innovationsfonds/Versorgungsforschung; Project name: Big Data - eHealth: Verbesserung der Versorgung von Kindern und Jugendlichen mit chronisch entzündlichen Darmerkrankungen (CED-KQN); Grant number: 01VSF17054