ACR, EULAR release first classification criteria for IgG4
The American College of Rheumatology and EULAR have officially released the first classification criteria for IgG4-related disease, emphasizing multifactorial presentation, blood tests or serology, radiological findings and pathology data.
“IgG4-[related disease] is now recognized to be a worldwide condition that is seen not only by rheumatologists but also generalists and sub-specialists of nearly every kind,” John H. Stone, MD, MPH, professor of medicine at Harvard Medical School and director of the international panel of experts who developed the new criteria, said in an ACR press release. “Clinical trials are now being developed in IgG4-[related disease] and investigators need criteria on which to base patients’ inclusion or exclusion for such trials and other types of investigation.”
The ACR and EULAR first presented a draft of their criteria at the 2018 ACR/ARP Annual Meeting, in Chicago. Since that time, the development team performed a second validation study, which included a cohort of 485 participants — 321 cases and 164 mimickers — to confirm sensitivity and specificity. The completed and approved set of classification criteria have been laid out in a special article published simultaneously in Arthritis & Rheumatology and the Annals of the Rheumatic Diseases.
The international panel that developed the criteria included 86 physicians representing five continents, assembled by the ACR and EULAR. Together, they used consensus exercises, a literature review, derivation and validation cohorts totaling 1,879 participants — 1,086 cases and 793 mimickers — and multi-criterion decision analysis to identify, weight and test potential criteria.
The criteria describe a three-step process in classifying patients with the disease, in which providers must carefully assess data from four domains. These are clinical presentation, the results of blood tests or serology, radiological findings and pathology data. All of these domains must be included in the assessment, as there is no single diagnostic test for IgG4-related disease.
Specifically, in the first step, researchers must demonstrate that a potential case of IgG4-related disease features involvement of at least one of 11 possible organs in a manner consistent with the condition. The second step takes features exclusion criteria, including 32 clinical, serologic, radiologic and pathologic items that must be applied, according to the panel. Third, researchers must apply eight weighted inclusion criteria domains, addressing clinical findings, serologic results, radiology assessments and pathology interpretations.
The first validation cohort included a threshold of 20 points, and revealed a specificity of 99.2% (95% CI, 97.2-99.8) and a sensitivity of 85.5% (95% CI, 81.9-88.5). In the second validation cohort, the specificity was 97.8% (95% CI, 93.7-99.2) and a sensitivity of 82% (95% CI, 77-86.1).
“IgG4-[related disease] is a disease that tends to afflict middle-aged to elderly individuals and often affects and damages the pancreas severely, making glucocorticoids a suboptimal therapy for this condition,” Stone said in the release. “Clinical trials will help develop targeted therapies that spare toxicities from conventional treatments. Investigators need to have criteria like this to determine whether a patient should be classified as having IgG4-[related disease].” – by Jason Laday
Disclosure: The authors report no relevant financial disclosures.