David G. I. Scott

Development and validation of a consensus methodology for the classification of the ANCA-associated vasculitides and polyarteritis nodosa for epidemiological studies

Background: The classification of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and polyarteritis nodosa (PAN) for epidemiology studies is confusing. The existing schemes such as American College of Rheumatology (ACR) criteria, Chapel Hill Consensus Conference (CHCC) definitions and Lanham criteria produce overlapping and conflicting classifications, making it difficult to compare incidence figures. Aim: To develop a consensus method of using these criteria and definitions for epidemiological studies to permit comparison without confounding by classification. Methods: A stepwise algorithm was developed by consensus between a group of doctors interested in the epidemiology of vasculitis. The aim was to categorise patients with Wegener’s granulomatosis, microscopic polyangiitis (MPA), Churg–Strauss syndrome (CSS) and PAN into single clinically relevant categories. The ACR and Lanham criteria for CSS, and ACR criteria for Wegener’s granulomatosis were applied first, as these were considered to be the most specific. Surrogate markers for Wegener’s granulomatosis were included to distinguish Wegener’s granulomatosis from MPA. MPA was classified using the CHCC definition and surrogate markers for renal vasculitis. Finally, PAN was classified using the CHCC definition. The algorithm was validated by application to 20 cases from each centre and 99 from a single centre, followed by a paper case exercise. Results: A four-step algorithm was devised. It successfully categorises patients into a single classification. There was good correlation between observers in the paper case exercise (91.5%; unweighted κ = 0.886). Conclusion: The algorithm achieves its aim of reliably classifying patients into a single category. The use of the algorithm in epidemiology studies should permit comparison between geographical areas.

EULAR recommendations for conducting clinical studies and/or clinical trials in systemic vasculitis: focus on anti-neutrophil cytoplasm antibody-associated vasculitis

Objectives: To develop the European League Against Rheumatism (EULAR) recommendations for conducting clinical studies and/or clinical trials in systemic vasculitis. Methods: An expert consensus group was formed consisting of rheumatologists, nephrologists and specialists in internal medicine representing five European countries and the USA, a clinical epidemiologist and representatives from regulatory agencies. Using an evidence-based and expert opinion-based approach in accordance with the standardised EULAR operating procedures, the group identified nine topics for a systematic literature search through a modified Delphi technique. On the basis of research questions posed by the group, recommendations were derived for conducting clinical studies and/or clinical trials in systemic vasculitis. Results: Based on the results of the literature research, the expert committee concluded that sufficient evidence to formulate guidelines on conducting clinical trials was available only for anti-neutrophil cytoplasm antibody-associated vasculitides (AAV). It was therefore decided to focus the recommendations on these diseases. Recommendations for conducting clinical trials in AAV were elaborated and are presented in this summary document. It was decided to consider vasculitis-specific issues rather than general issues of trial methodology. The recommendations deal with the following areas related to clinical studies of vasculitis: definitions of disease, activity states, outcome measures, eligibility criteria, trial design including relevant end points, and biomarkers. A number of aspects of trial methodology were deemed important for future research. Conclusions: On the basis of expert opinion, recommendations for conducting clinical trials in AAV were formulated. Furthermore, the expert committee identified a strong need for well-designed research in non-AAV systemic vasculitides.

Epidemiology of systemic vasculitis: a ten-year study in the United Kingdom.

OBJECTIVE To describe the epidemiology of the primary systemic vasculitides (PSV; Wegeners granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, polyarteritis nodosa) in a well-defined population over a 10-year period. METHODS An inception cohort of patients from the Norwich Health Authority (NHA) who were >15 years of age and had PSV first diagnosed between January 1, 1988 and December 31, 1997 was collected. Incidence rates were adjusted for age and sex to the 1992 population. The prevalence of PSV in this cohort was estimated on December 31, 1997. Patients were classified according to the American College of Rheumatology 1990 vasculitis criteria and the Chapel Hill Consensus definitions. RESULTS Eighty-two NHA residents fulfilled the inclusion criteria. There were 47 men and 35 women, with a mean age of 62.9 years (median 65.0 years). The overall annual incidence of PSV among NHA residents was 19.8/million (95% confidence interval [95% CI] 15.8-24.6). The point prevalence on December 31, 1997 was 144.5/million (95% CI 110.4-185.3). PSV was more common in males (23.5/million; 95% CI 17.3-31.3) than females (16.4/million; 95% CI 11.4-22.8). The age- and sex-specific incidence showed a clear increase with age, with an overall peak in the 65-74 year age group (60.1/million). CONCLUSION In our study population, the annual incidence of PSV is slowly increasing with time and the incidence is greatest in the elderly.

Epidemiology of Systemic Vasculitis: Changing Incidence or Definition?

The epidemiology of the systemic vasculitides is poorly documented. Many studies have been conducted from tertiary referral centers, with resulting problems of referral bias and uncertainty of denominator population, or have involved small populations. We have estimated the incidence of the major forms of systemic vasculitis in a stable, ethnically homogeneous population of 414,000 adults from 1988 to 1994. The overall annual incidence of systemic vasculitis (excluding giant cell arteritis) is 39/million (95% confidence intervals; ranging from 31 to 47). The annual incidence of Wegeners granulomatosis is 8.5/million (range, 5.2 to 12.9), Churg-Strauss syndrome 2.4/million (0.9 to 5.3), microscopic polyangiitis 2.4/million (0.9 to 5.3), adult Henoch-Schonlein purpura 1.2/million (0.3 to 3.5), and systemic rheumatoid vasculitis 12.5/million (8.5 to 17.7). These data suggest that the overall incidence of systemic vasculitis is greater than previously thought (10/million) with Wegeners granulomatosis and systemic rheumatoid vasculitis being the most common. Whether this represents a genuine increase in incidence or increased physician awareness is uncertain.

Intravenous cyclophosphamide plus methylprednisolone in treatment of systemic rheumatoid vasculitis

Systemic vasculitis in rheumatoid arthritis shows similarities to polyarteritis nodosa and may require equally aggressive therapy. Forty-five patients with systemic rheumatoid vasculitis were studied during treatment with either cyclophosphamide plus methylprednisolone given by intermittent bolus intravenous injection (21 patients) or a variety of other more conventional drug regimens (24 patients). In this open study, the intravenous treatment group had more severe initial disease, a higher incidence of neuropathy, and more frequent evidence of necrotizing arteritis on biopsy than the other treatment group. Despite this, intravenous cyclophosphamide plus methylprednisolone resulted in more frequent healing of vasculitic lesions including leg ulcers and neuropathy, a lower incidence of relapse, fewer serious complications, and a lower mortality than did other treatments. Toxic effects were similar in both study groups. Intravenous cyclophosphamide plus methylprednisolone is a useful early treatment for systemic rheumatoid vasculitis.

Comparison of the epidemiology of anti-neutrophil cytoplasmic antibody-associated vasculitis between Japan and the UK

OBJECTIVES The epidemiological manifestations of ANCA-associated vasculitis (AAV) differ geographically. However, there have been no prospective studies comparing the incidence of AAV between Japan and Europe over the same time period using the same case definitions. METHODS The incidence of AAV was determined by a population-based method in Miyazaki prefecture, Japan, and Norfolk, U.K., between 2005 and 2009. Patients with AAV were defined and classified according to the European Medicines Agency (EMEA) algorithm. RESULTS The number of incident cases of AAV in Japan and the U.K. were 86 and 50, respectively, and the average annual incidence over the 5-year period was 22.6/million (95% CI 19.1, 26.2) and 21.8/million (95% CI 12.6, 30.9) in Japan and the U.K., respectively. The average age was higher in patients in Japan than in patients in the U.K. [mean (median), 69.7 (72) vs. 60.5 (61) years]. Microscopic polyangiitis (MPA) was the predominant subtype in Japan (83%), while granulomatosis with polyangiitis (Wegeners) was more frequent in the U.K. (66%). As for the pattern of ANCA positivity, >80% of Japanese patients were pANCA/MPO positive, whereas two-thirds of U.K. patients were cANCA/PR3 positive. Renal involvement in MPA was very common in both countries, but was much less common in granulomatosis with polyangiitis in Japan compared with the U.K. CONCLUSION There was no major difference in AAV incidence between Japan and the U.K., but this prospective study found MPA and MPO-ANCA to be more common in Japan and granulomatosis with polyangiitis and PR3-ANCA to be more common in the U.K., in line with earlier reports.

Epidemiology of ANCA-associated Vasculitis

The epidemiology of the antineutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAV), comprising Wegeners granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome, poses considerable challenges to epidemiologists. These challenges include the difficulty of defining a case with a lack of clear distinction between the different disorders, case capture, and case ascertainment. The AAV are rare and therefore a large population is required to determine the incidence and prevalence, and this poses questions of feasibility. Despite these difficulties a considerable body of data on the epidemiology of the AAV has been built in the past 20 years with an interesting age, geographic, and ethnic tropism gradually being revealed. Most of the data come from White populations of European descent, and the overall annual incidence is estimated at approximately 10-20/million with a peak age of onset in those aged 65 to 74 years.

Genetic Linkage of the Muckle-Wells Syndrome to Chromosome 1q44

The Muckle-Wells syndrome (MWS) is a hereditary inflammatory disorder characterized by acute febrile inflammatory episodes comprising abdominal pain, arthritis, and urticaria. Progressive nerve deafness develops subsequently, and, after several years, the disease is complicated by multiorgan AA-type amyloidosis (i.e., amyloidosis derived from the inflammatory serum amyloid-associated protein) (MIM 191900) with renal involvement and end-stage renal failure. The mode of inheritance is autosomal dominant, but some sporadic cases have also been described. No specific laboratory findings have been reported. The genetic basis of MWS is unknown. Using a genomewide search strategy in three families, we identified the locus responsible for MWS, at chromosome 1q44. Our results indicate that the gene is located within a 13.9-cM region between markers D1S2811 and D1S2882, with a maximum two-point LOD score of 4. 66 (recombination fraction.00) at D1S2836 when full penetrance is assumed. Further identification of the specific gene that is responsible for MWS will therefore provide the first biological element for characterizing MWS, other than doing so on the basis of its variable clinical expression.

1 Classification and epidemiology of the vasculitides

The systemic vasculitides are rare inflammatory conditions of blood vessel walls. A number of different classification schemes have been published since the first in 1952. The important developments have been the recognition of dominant blood vessel size, the distinction between primary and secondary vasculitis and the incorporation of pathogenic markers such as anti-neutrophil cytoplasmic antibodies. In 1990 the American College of Rheumatology (ACR) published criteria for the diagnosis of polyarteritis nodosa, Churg-Strauss syndrome, Wegeners granulomatosis, hypersensitivity vasculitis, Schonlein-Henoch purpura, giant cell arteritis and Takayasu arteritis. Sensitivity and specificity rates varied considerably: 71.0–95.3% for sensitivity and 78.7–99.7% for specificity. The critieria were not tested against the general population or against patients with other connective tissue diseases or rheumatic conditions. Four years later the Chapel Hill Consensus Conference (CHCC) produced definitions for the major types of vasculitis, however, these have proved controversial. Comparison in unselected patients with systemic vasculitis (in particular polyarteritis nodosa and microscopic polyangiitis) has shown that the ACR criteria and CHCC definitions identify different patients. The systemic vasculitides are somewhat more common than previously believed. The overall annual incidence approaches 40/million adults. The most common form of primary systemic vasculitis is giant cell arteritis; Wegeners granulomatosis, microscopic polyangiitis and Churg-Strauss syndrome have similar incidences. Classical polyarteritis nodosa and Takayasu arteritis are very rare in the UK.

Recommendations for the use of rituximab in anti-neutrophil cytoplasm antibody-associated vasculitis

OBJECTIVES To perform a literature review and develop recommendations for the use of rituximab in ANCA-associated vasculitis. METHODS A committee of experts (five rheumatologists, five nephrologists and one paediatrician) conducted a modified Delphi exercise to identify five topics for a systematic literature search. The evidence was then reviewed, categorized according to international criteria and assimilated to form five recommendations statements and a research agenda. RESULTS Forty-three studies met the review criteria. These included two randomized controlled trials and a predominance of small, uncontrolled series. In refractory ANCA-associated vasculitis, remission rates of >80% are obtained with rituximab. In newly diagnosed disease, rituximab is at least as effective as conventional therapy. Fifteen recommendations were made. Their strength was restricted by the low quality of the evidence. Six areas for future research were identified. CONCLUSION On the basis of the available evidence and expert consensus, recommendations have been made for the use of rituximab as a treatment of ANCA-associated vasculitis. Further questions, in particular regarding long-term outcomes, remain to be explored.