Duration of Azathioprine Maintenance in AAV Does Not Alter Relapse Rates Save

A European multicentre study examined whether the duration of azathioprine (AZA) maintenance therapy in ANCA-associated vasculitis patients would influence the relapse rate during long-term follow-up.

Investigators enrolled 380 ANCA-associated vasculitis patients currently treated with AZA maintenance therapy. The diagnoses were primarily granulomatosis with polyangiitis (n = 236) but also included microscopic polyangiitis (n = 132) and renal limited vasculitis ( n = 12). 

There were 84 first relapses while on AZA-maintenance therapy (1 relapse per 117 patient months) and 71 after withdrawal of AZA (1 relapse/113 months).

In those who stopped AZQ, there were 20 relapses in the first 12 months (1 relapse/119 months) and 29 relapses beyond 12 months after withdrawal (1 relapse/186 months).

Relapse-free survival at 60 months was 65.3% for patients receiving AZA maintenance >18 months diagnosis vs 55% for those who discontinued maintenance ⩽18 months (P = 0.11). Relapse-free survival was more likely in those based on induction therapy (i.v. vs oral) and ANCA specificity (PR3-ANCA vs MPO-ANCA/negative).

It appears that stopping AZA maintenance therapy does not lead to a significant increase in relapse rate and AZA maintenance for more than 18 months does not alter relapse-free survival rates. ANCA specificity has more effect on relapse-free survival than duration of maintenance therapy and should be used to tailor therapy individually.