LAUSR

OBJECTIVES Despite the identification of risk factors for relapses in anti-neutrophil cytoplasmic antibody-associated vasculitis, the relationship between changes in C-reactive protein levels after initial treatment and incidence of relapse remains unknown. This study aimed to assess the association between the time taken for normalisation of C-reactive protein levels and the incidence of relapse in Japanese adult patients with microscopic polyangiitis. METHODS This study included 85 consecutive patients with newly diagnosed microscopic polyangiitis who achieved remission after six months of immunosuppressive treatment at the Aichi Medical University Hospital, between 2009 and 2017. The relationship between the time to normalisation of C-reactive protein after initial immunosuppressive treatment and relapse incidences was evaluated using multivariable Cox proportional hazard models. RESULTS During the follow-up period, 13 (30.2%), 7 (41.2%), and 16 (64.0%) patients relapsed (P=0.025) within 1-14, 15-28, and ≥29 days of normalisation, respectively. Hazard ratios (95% confidence intervals) of the time to normalisation of C-reactive protein of 1-14, 15-28, and ≥29 days were 1.00 (reference), 2.42 (95%CI: 0.92-6.39), and 3.48 (95%CI: 1.56-7.76), respectively. CONCLUSIONS A significant association between the time to normalisation of C-reactive protein and relapse incidence in Japanese patients with microscopic polyangiitis was observed.