Long-Term Outcome And Efficacy Of Cyclophosphamide Therapy In Japanese Patients With Anca-Associated Microscopic Polyangiitis: A Retrospective Study

Objective The aim of this study was to elucidate the efficacy of cyclophosphamide (CY) in Japanese patients with antineutrophil cystoplasmic antibody (ANCA)-associated microscopic polyangiitis (MPA).Methods Sixty-four patients, newly diagnosed with ANCA-associated MPA were included in this retrospective study. The patients were divided into two groups based on whether they received combination therapy of CY and corticosteroid (CS) (CY group, n=29) or CS alone (CS group, n=35) for remission induction. The primary outcome was all-cause mortality.Results Most patients in the CY group were treated with oral CY. Between the two groups, there were no differences in the baseline characteristics except for a higher proportion of male patients in the CY group. The remission rate was not substantially different between the two groups (86.2% in the CY group vs. 91.4% in the CS group). The survival rate was slightly higher in the CY group than in the CS group (not statistically significant; 0.86 vs. 0.77 at 1 year and 0.73 vs. 0.64 at 5 years, p=0.648). In the CY group, the hazard ratio after adjusting for age, sex, Birmingham vasculitis activity score values, serum albumin levels and C-reactive protein (CRP) levels was 0.657 (95% CI, 0.254-1.699; p=0.386).Conclusion We observed no increased efficacy of CY in ANCA-positive MPA in the Japanese patients, and hence, its efficacy may be limited in these patients.