Association of the AAV-PRO questionnaire with established outcome measures in AAV

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.

In a prospective longitudinal study, AAV-PRO, Beck's depression inventory (BDI), Short Form 36 (SF-36), 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 analysed by t-tests and correlation-based regression analyses.

A total of 156 patients with AAV participated. The mean BVAS at the time of enrolment was 1.4 ± 3.74. The median AAV-PRO domain scores were higher in patients reporting 'active disease' compared with those 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 with all eight SF-36 subdomains (all |r|≥0.267, all P ≤ 0.001). The regression analyses showed that AAV-PRO domains were strongly predicted by the BDI and SF-36 domains (|β| ≥ 0.240 for the strongest predictor of each domain). In the longitudinal comparison (t1/t2), there were no significant changes in the overall results.

Our data show convergent validity for all AAV-PRO subdomains, using the established questionnaires BDI and SF-36. The AAV-PRO domains scores were not correlated with clinician-derived instruments (including the BVAS and the VDI). Thus, we regard the AAV-PRO questionnaire as a valuable measure of outcomes that might complement traditional end-points in clinical trials.