Background: Wegener's granulomatosis (WG), Churg Strauss syndrome (CSS) and microscopic polyangiitis (MPA) are primary systemic vasculitides (PSV), the clinical features of which have been described from tertiary centres.
Aim: To provide the first clinical description of MPA from a general hospital and compare clinical features with WG and CSS.
Design: Retrospective analysis of patient records.
Methods: Records of 99 PSV patients attending a single hospital, from 1988 to 2000, were reviewed for: clinical features, date/age at diagnosis, sex, duration of illness, anti-neutrophil cytoplasmic antibodies (ANCA), treatment, comorbidity and deaths. Cases were classified using ACR, CHCC and Lanham criteria/definitions. Birmingham vasculitis activity scores (BVAS) and damage index (VDI) were calculated. Survival was assessed using Cox proportional hazards model and standardized mortality ratios (SMRs).
Results: Compared to previous reports there was more ENT (29%) and respiratory (29%) but less renal (92%) involvement in MPA, and less ENT involvement in WG (81%). CSS showed high neurological (72%), cardiovascular (28%) and gastrointestinal (17%) involvement and the highest median (range) VDI (p = 0.01 vs. WG; p = 0.001 vs. MPA). BVAS1 was significantly lower in MPA than in WG [median (range) 15 (4-29) vs. 21 (6-39), (p = 0.001)] but not in CSS [20 (7-28), p = 0.08]. SMR (95%CI) for PSV was 4.8 (3.0-6.6); 5-year survival was 45.1% for MPA, 75.9% for WG and 68.1% for CSS. Age was a significant risk, but only to the same extent as in the reference population. When age was adjusted for, no other significant factor was found.
Discussion: The clinical characteristics seen here are similar to those in previous series. There are difficulties in using the MPA CHCC definitions in classification. There is a high proportion of neurological involvement in CSS, causing permanent damage. MPA may have a poorer prognosis than WG or CSS.