[Clinical features of Wegener granulomatosis and microscopic polyangiitis in Chilean patients]

Systemic vasculitis are a group of heterogeneous diseases characterized by inflammation and necrosis of blood vessel walls. The etiology is not known, but geographic and environmental factors are implicated.

To describe the clinical features of microscopic polyangiitis (MPA) and Wegener's granulomatosis (WG) in a Chilean cohort of patients.

Retrospective review of the medical records of 123 patients with the diagnosis of systemic vasculitis (65 MPA and 58 WG), seen from 1990 to 2001. The diagnosis were made based on the American College of Rheumatology and Chapel Hill criteria.

The mean follow-up for MPA was 15 months (1-120) and for WG, 20 months (1-120). The median age (years) at diagnosis for MPA was 61 (19-82) and WG 50 (20-82). Gender distribution was similar in both groups (male: 68% and 57% respectively). The main clinical features in the MPA group were renal involvement (68%), peripheral nervous system involvement (57%), pulmonary hemorrhage (28%), and skin disease (32%). In the WG group were alveolar hemorrhage (62%), renal involvement (78%), paranasal sinus involvement (57%), and ocular disease (26%). In both, creatinine levels above 2.0 mg/dl were associated with a higher mortality (p< 0.01). ANCA by immunofluorescence was performed in 56 MPA patients (75% had pANCA, 4% had cANCA and 21% were ANCA negative) and in 55 WG patients (17% had pANCA, 79% had cANCA and 4% were ANCA negative). Global mortality was 18% and 17% respectively, and the most common causes of death were infections.

The clinical features of our patients are similar to other published data. In our WG and MPA patients the main predictor for death was a serum creatinine above 2 mg/dl.