The Longitudinal Course of Fatigue in Anca Associated Vasculitis

OBJECTIVE: Fatigue is common and burdensome in ANCA-associated vasculitis (AAV). This study aimed to understand how fatigue changes over time following treatment initiation and determine whether individuals with the poorest prognosis can be robustly identified.

METHODS: 149 patients with AAV and new onset disease recruited to two clinical trials (RITUXIVAS and MYCYC) were followed for 18 months. Fatigue was measured at baseline and 6 monthly intervals using the vitality domain of the SF-36 quality of life questionnaire and compared to a cohort of 470 controls. Group-based trajectory modelling (GBTM) determined trajectories of the symptom between which baseline characteristics and on-going fatigue scores were compared.

RESULTS: Fatigue levels at diagnosis were worse in patients than controls (median 30 IQR 10, 48 vs 70 IQR 55, 80; p<0.001), with 46% of patients reporting severe fatigue. Fatigue improved after 6 months treatment but remained worse than controls (p<0.001). GBTM revealed varied trajectories of fatigue: low fatigue stable (n=23), moderate baseline fatigue improver (n=29), high baseline fatigue improver (n=61) and stable baseline high fatigue (n=37). Participants who followed stable high fatigue trajectories had lower vasculitis activity compared to improvers but no other demographic or clinical variables differed.

CONCLUSION: This study longitudinally measured fatigue levels in patients with AAV. Although, most patients improve following treatment, an important subgroup of patients report persistent high levels of fatigue that does not change. Few clinical or laboratory markers distinguished these patients, suggesting alternative interventions specific for fatigue are required.