Long-term follow-up of microscopic polyangiitis, 17-year experience at a single center

Long-term prognoses of Wegener granulomatosis (WG) and Churg-Strauss syndrome (CSS) are known; however, few data exist on long-term prognoses for microscopic polyangiitis (MPA). Our aim was to analyse the prognoses of MPA.Cohort study with retrospective selection of patients. Twenty-two patients admitted to our Hospital (1990-2006) with biopsy-proven MPA were studied. The start date for entry into the study was the date of diagnosis. Statistical analysis was performed to look for prognostic factors for survival.MPA patients were followed-up for a median of 78 (5-131) months. MPA patients were treated with cyclophosphamide (Cy) plus corticosteroid (Cs) (59%) or Cs alone (41%). Seven MPA patients died. Cumulative MPA patient survival at 1, 5, and 10 years were 85% (75-95%), 85% (75-95%), and 74% (60-88%) in those treated with Cy plus Cs and 50% (32-68%), 36% (14-58%), and 0% (0-30%) in those treated with Cs alone, respectively (P=0.04). Disease extent index5 (P=0.02) and age65 years (P=0.02) were associated with improved survival rates in MPA patients treated with Cy. Five MPA (23%) patients relapsed after a median of 54 months (35-93). No variables were related to relapses. Despite treatment, 11MPA (50%) patients developed end-stage renal disease after a median of 9 months (0-53).Most MPA patients had life-threatening renal or lung involvement at diagnosis. Patients not treated with immunosuppressants had a poorer prognosis. The long-term prognosis of MPA patients who survived 6 months post diagnosis was good, although renal survival rates are low.