Comparison of disease activity measures for anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis.

AIM: Currently, several different instruments are used to measure disease activity and extent in clinical trials of anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis, leading to division among investigative groups and difficulty comparing study results. An exercise comparing six different vasculitis instruments was performed. METHODS: A total of 10 experienced vasculitis investigators from 5 countries scored 20 cases in the literature of Wegener granulomatosis or microscopic polyangiitis using 6 disease assessment tools: the Birmingham Vasculitis Activity Score (BVAS), The BVAS for Wegener granulomatosis (BVAS/WG), BVAS 2003, a Physician Global Assessment (PGA), the Disease Extent Index (DEI) and the Five Factor Score (FFS). Five cases were rescored by all raters. RESULTS: Reliability of the measures was extremely high (intraclass correlations for the six measures all = 0.98). Within each instrument, there were no significant differences or outliers among the scores from the 10 investigators. Test/retest reliability was high for each measure: range = 0.77 to 0.95. The scores of the five acute activity measures correlated extremely well with one another. CONCLUSIONS: Currently available tools for measuring disease extent and activity in ANCA-associated vasculitis are highly correlated and reliable. These results provide investigators with confidence to compare different clinical trial data and helps form common ground as international research groups develop new, improved and universally accepted vasculitis disease assessment instruments.

Prevalence of Wegener's granulomatosis, microscopic polyangiitis, polyarteritis nodosa and Churg-Strauss syndrome within a defined population in southern Sweden.

OBJECTIVES: To estimate the point prevalence (p.p.) of Wegener's granulomatosis (WG), microscopic polyangiitis (MPA), polyarteritis nodosa (PAN) and Churg-Strauss syndrome (CSS) within a defined population in southern Sweden. METHOD: A cross-sectional p.p. study using multiple sources for case identification. The study area, a healthcare district around the city of Lund in southern Sweden (Mellersta Skånes sjukvårdsdistrikt), had, on 31 December 2002, a total population of 287 479 inhabitants. All the identified cases were verified by medical record review. The patients were classified according to an algorithm based on the American College of Rheumatology classification criteria 1990 and the Chapel Hill Consensus Conference definitions 1994. RESULTS: Eighty-six patients (49% female) with a median age of 64.8 yrs (range 15-90.5) fulfilled the study criteria. There were 46 patients with WG; 27 with MPA; nine with PAN; and four with CSS. The p.p. per million inhabitants was estimated on 1 January 2003 to be 160 (95% confidence interval 114-206) for WG, 94 (58-129) for MPA, 31 (11-52) for PAN and 14 (0.3-27) for CSS. Capture-recapture analysis estimated the completeness of the case finding to 96%. CONCLUSIONS: The prevalence of WG, MPA, PAN and CSS in our district is the highest figure reported so far. Explanations for this finding may include high incidence, extensive ANCA-testing, good survival as well as sensitive search methods for case identification.

Epidemiology of Wegener's granulomatosis: Lessons from descriptive studies and analyses of genetic and environmental risk determinants.

During the past 15 years, the epidemiology of Wegener's granulomatosis (WG) has become better understood. Descriptive epidemiological studies carried out primarily in European countries estimate a prevalence of WG ranging from 24 to 157 per million and annual incidence rates from 3 to 14 per million. These studies suggest a North-South declining gradient in disease risk in the Northern Hemisphere and an increase in incidence over time, although the latter is likely largely due to improved diagnostic ascertainment. Data also indicate the presence of potential secular and seasonal variations in WG incidence and a decreasing disease risk among non-Caucasians. Furthermore, analytic epidemiological studies have pointed out putative genetic and non-genetic risk factors for WG. Genetic investigations have identified various candidate genes, with alpha1-antitrypsin deficiency being the most consistently reported genetic susceptibility factor to date. Even though much less research has been devoted to environmental risk factors, evidence has grown for a possible relationship between WG and occupational exposure to crystalline silica. Thus far, data support the concept of WG as a multifactorial disease in which genetic and environmental determinants are involved but a major gap in understanding persists regarding the extent to which both factors contribute to its development. This and many other questions remain to be answered by future structured epidemiological research. This review focuses on the current knowledge of descriptive epidemiology and genetic and environmental factors associated with WG.