Association of the ANCA-associated vasculitis (AAV) patient-reported outcome (AAV-PRO) questionnaire with established outcome measures in AAV

Objectives The ANCA-associated vasculitis (AAV) patient-reported outcome (AAV-PRO) questionnaire was developed to capture the impact of AAV and its treatment. We investigated the association of specific AAV-PRO domains with disease activity and extent, damage, depression, health-related quality of life and treatment. Methods In a prospective longitudinal study AAV-PRO, Beck’s depression inventory (BDI), Short Form 36 (SF36), BVAS and Vasculitis Damage Index (VDI) were completed at baseline (t1) and after 3–6 months (t2). In addition, patient data including diagnosis, therapies, relapses, and organ manifestations were recorded. Data were analyzed by t-tests and correlation-based regression analyses. Results 156 patients with AAV participated. The mean BVAS at the time of enrolment was 1.4 ± 3.74. Median AAV-PRO domain scores were higher in patients reporting “active disease” compared with patients reporting “in remission” (p< 0.001). In the correlation analyses all AAV-PRO domain scores correlated strongly with the BDI (all r ≥ 0.319, all p≤ 0.001) as well as all eight SF36 subdomains (all |r|≥0.267, all p≤ 0.001). The regression analyses showed that AAV-PRO domains were strongly predicted by BDI and SF36 domains (|β|≥0.240 for the strongest predictor of each domain). In the longitudinal comparison (t1/t2) there were no significant changes of the overall results. Conclusion Our data show convergent validity of all AAV-PRO subdomains with the established questionnaires BDI and SF-36. The AAV-PRO domains scores were not correlated with clinician derived instruments including the BVAS and VDI. Thus, we regard the AAV-PRO as a valuable addition that might complement traditional endpoints in clinical trials