Classification Criteria and Diagnostic Tests for Vasculitides

Abstract

Most rheumatic diseases, in adults or children, do not have objective clinical or laboratory measures that allow physicians to diagnose a specific disease with certainty. In order to overcome the clinical dilemma of a proper diagnosis, classification criteria have been proposed for several rheumatic diseases. Classification criteria are therefore an essential tool for clinical research since they allow comparison of patients with similar clinical and laboratory characteristics across studies. In the vasculitis research field several classification criteria have been proposed for the adult population, and more recently for children. These criteria have been derived through 2 major methodological approaches: consensus and consensus/data-driven. In brief, the consensus-based criteria are specifically derived through the combination of judgments from a group of experts in a particular field after thorough literature review and sometimes developed using consensus techniques such as the Delphi technique and nominal group technique1,2. To the consensus-based criteria we can ascribe the Chapel Hill International Consensus Conference3 that essentially provided proper nomenclature for systemic vasculitides, and the Childhood Vasculitis Working Group of the Paediatric Rheumatology European Society (PRES) for preliminary classification criteria of childhood vasculitis4. These criteria have their main strength in the panel of contributors who are usually very well recognized experts/experienced clinicians in that particular research/clinical field. The second approach of consensus/data-driven usually starts from consensus-based criteria and adds a formal statistical validation based on collected data in order to provide accuracy measures (classic methods), or other alternative methods such as the classification tree5. Only the classical approach is discussed here. With the classic approach, the accuracy measures that are considered include sensitivity (ability of a classification criterion to identify a patient as having the disease based on a gold standard; also called true-positive rate); specificity (ability of classification criteria … Address correspondence to Dr. Ruperto; E-mail: nicolaruperto{at}ospedale-gaslini.ge.it