ACR, EULAR Classification Criteria for Granulomatosis With Polyangiitis (Part 2)
This week, please let me introduce properly our topic.
The antineutrophil cytoplasmic antibody (ANCA)–associated vasculitides (AAV) are multisystem disorders linked with the inflammation of the small blood vessels and include granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA).
GPA is seen as necrotizing granulomatous inflammation involving the ears, nose, and upper and lower respiratory tracts, and necrotizing vasculitis affecting predominantly small- to medium-sized vessels, often including necrotizing glomerulonephritis.
The purpose of classification criteria is to ensure that a homogeneous population is chosen for inclusion in clinical trials and studies of GPA.
In 1990, the American College of Rheumatology (ACR) came up with a criteria for the classification of GPA.
The 1990 criteria were effective and accepted in facilitating approaches to international randomized controlled trials.
The 1994 and 2012 publications of the international Chapel Hill Consensus Conference (CHCC) nomenclature for vasculitis clarified and standardized the names of the systemic vasculitides. The CHCC is a system based on expert consensus.
There are several important reasons for the development of revised classification criteria for the vasculitides, including a decline in the sensitivity of the 1990 ACR classification criteria, particularly for AAV.
The consensus was the criteria must now incorporate testing for ANCA.
There have been widespread use of cross-sectional diagnostic imaging tools, including magnetic resonance imaging and computed tomography; and the introduction and adoption of the classification of patients with MPA, a term that was not in use in the 1990 ACR criteria.
There have been advances in the derivation of classification criteria, moving from the “number of criteria” rule, toward weighted criteria with threshold scores, as demonstrated in the 2010 classification criteria for rheumatoid arthritis.
The weighted criteria improve the properties of classification because certain items within a criteria list may be more distinct.
We will continue with this discussion next week as we engage in the introduction of this type of disease.