Background/Purpose: The lack of standardized definitions and descriptors for clinical manifestations of giant cell arteritis (GCA) leads to variable interpretations of findings in clinical practice and research settings. An international task force developing response criteria for GCA addressed this shortcoming by developing a glossary of definitions for signs and symptoms of GCA. 

This glossary aims to create a consensus-based definition of signs and symptoms of GCA to be used by healthcare professionals, primarily in research settings.

Methods: Core definitions or descriptors of signs and symptoms of GCA were extracted from 11 randomized controlled trials. These trials were part of a systematic literature review published by the task force working on developing response criteria for GCA. This information was supplemented by definitions or descriptors from rheumatology textbooks, the 2022 ACR/EULAR Classification Criteria for GCA, the ACR 1990 Classification Criteria of GCA and a Delphi exercise conducted as part of the response criteria for GCA project.

The scientific committee identified general principles deemed important for the interpretation and application of definitions. A 2-round Delphi exercise was conducted. The first round aimed to obtain consensus on the descriptive terms to define each sign or symptom obtained from the literature review; >70% agreement=the descriptor was accepted; < 30% agreement = the descriptor was excluded; 30-70% agreement = the descriptor was reassessed in the 2nd round. Round 2 of the Delphi exercise rated the importance of each descriptor: not important, important, or critically important. Those descriptors rated critically important were incorporated into the definitions. Those descriptors without consensus ratings were discussed via virtual meetings. Based on the Delphi, preliminary definitions of the signs and symptoms of GCA were developed.

Three virtual meetings were then conducted during which the results of the Delphi exercise and the preliminary definitions of the signs/symptoms of GCA were discussed. Through an online live voting process, task force members reached consensus on the definition of each term if >75% agreed on the refined definition. A similar voting process was established if a definition was not necessary.

Results: 29 task force members from 11 countries participated in the two Delphi rounds and three virtual meetings. Two overarching principles were formulated by consensus (Table 1).

A total of 27 signs and symptoms of GCA were reviewed, with 24 retained for defining. 12/24 signs for symptoms of GCA were not included in the glossary because they were considered either self-explanatory, rare occurrences or not indicative of a highly specific sign or symptom related to GCA. A high level of consensus was reached on the definition of 12 signs and symptoms of GCA (Table 1).

Conclusion: A glossary of definitions for 12 signs and symptoms of GCA was developed through a consensus process among international experts. These definitions are intended for use in research. Applying these definitions should facilitate uniform characterization of GCA features and harmonize enrollment of patients into clinical trials in GCA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-lexicon-of-signs-and-symptoms-of-giant-cell-arteritis-an-international-expert-consensus/