Incidence and survival rates in Wegener's granulomatosis, microscopic polyangiitis, Churg–Strauss syndrome and polyarteritis nodosa

Mohammad, Aladdin J.
Jacobsson, Lennart T. H.
Westman, Kerstin W. A.
Sturfelt, Gunnar
Segelmark, Mårten

¹Department of Nephrology, Lund University Hospital, Lund, Sweden
²Department of Internal Medicine, Helsingborg Hospital, Helsingborg, Sweden
³Department of Rheumatology, Malmö University Hospital, Malmö, Sweden
⁴Department of Nephrology and Transplantation, Malmö University Hospital, Malmö, Sweden
⁵Department of Rheumatology, Lund University Hospital, Lund, Sweden

Submitted 17 April 2009; revised version accepted 14 August 2009.

Correspondence to: Aladdin J. Mohammad, Department of Nephrology, Lund University Hospital, S-221 85 Lund, Sweden. E-mail: [email protected]

Rheumatology 48(12):p 1560-1565, December 2009.

Objective

To estimate the incidence of and survival rates for WG, microscopic polyangiitis (MPA), Churg–Strauss syndrome (CSS) and PAN within a defined population in southern Sweden.

Methods

Cases were retrieved using hospital records and a serology database. All new cases of WG, MPA, CSS and PAN between 1997 and 2006 were included, provided they met pre-defined criteria, and were followed until 30 June 2008. The study area comprised two health care districts with a total population of 641 000. The standardized mortality ratio (SMR) was estimated using Swedish population data as a reference.

Results

A total of 140 (WG, 63; MPA 65; CSS 6; and PAN 6) cases (52% women) with a median age of 67.6 (range 20–96) years fulfilled the inclusion criteria. The annual incidence per million of the population (95% CI) was estimated to be 9.8 (7.4–12.2) for WG, 10.1 (7.7–12.6) for MPA and 0.9 (0–1.7) for both CSS and PAN. The highest incidence was found in patients aged ≥75 years (79.1/million). The 1- and 5-year survival rates were 87.8 and 71.6% for all patients, but lower for MPA (80 and 55%) compared with WG (95 and 83%; P=0.001), although the difference was not significant in the multivariate analysis. The SMR was 2.77 (95% CI 2.02, 3.71) for all patients.

Conclusions

The incidence of WG and MPA was equal in our district, but there was a difference in survival rates related to age and renal function. A progressive increase in age-specific incidence rates was observed.