Validation of the German version of the ANCA-associated vasculitis patient-reported outcome questionnaire

This study aimed to validate the German version of the ANCA-associated vasculitis patient-reported outcome (AAV-PRO) measure by evaluating its psychometric properties.

Our study was a prospective cohort study of German speaking AAV patients, recruited in the rheumatology outpatient clinics at the University Hospital Düsseldorf. The questionnaire includes 29 items across six domains, each rated from 0 to 4 points. Participants completed the AAV-PRO (German) at three time points. They also completed the EuroQol-5D-5L (EQ-5D-5L) and self-reported their vasculitis status. The Birmingham Vasculitis Activity Score version 3 (BVASv3) and Vasculitis Damage Index (VDI) were completed by the treating physicians.

70 AAV patients (48.5% female) participated. Overall, fatigue was the most prevalent symptom. Female AAV patients reported higher symptom burden across all domains and had a higher total score (Z=-2.55, p=0.011). The AAV-PRO (German) demonstrated good internal consistency in the domains "social and emotional impact", "concerns about the future" and "physical function" (Cronbach's alpha≥0.83). The domain "systemic symptoms severity" demonstrates acceptable to good consistency. The other domains demonstrated insufficient consistency. All domains showed high test-retest reliability (Pearson r≥0.8). BVASv3 and VDI showed limited correlations with the AAV-PRO (German) domains. Construct validity was supported by moderate to strong correlations with the EQ-5D-5L in five domains. Patients with self-reported active disease had statistically significantly higher mean scores than those with self-reported inactive disease in three domains.

Our study supports the use of the AAV-PRO (German). However, two domains need to be interpreted carefully.