Incidence and survival rates in Wegener's granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome and polyarteritis nodosa.
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 >or=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.
Department of Nephrology, Lund University Hospital, Lund, Sweden. aladdin.mohammad@med.lu.se
Aladdin J
AJ
Mohammad
Lennart T H
LT
Jacobsson
Kerstin W A
KW
Westman
Gunnar
G
Sturfelt
Mårten
M
Segelmark
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015267:Churg-Strauss Syndrome / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D014890:Granulomatosis with Polyangiitis / Q000453:epidemiology; D006801:Humans; D008297:Male; D055953:Microscopic Polyangiitis / Q000453:epidemiology; D008875:Middle Aged; D010488:Polyarteritis Nodosa / Q000453:epidemiology; D012621:Seasons; D017678:Sex Distribution; D013548:Sweden / Q000453:epidemiology; D056647:Systemic Vasculitis / Q000453:epidemiology*; D055815:Young Adult