A Delphi exercise informing the development of criteria to measure response to treatment in giant cell arteritis.

To identify the most important and relevant items to consider when developing criteria to measure response to treatment in giant cell arteritis (GCA). As part of an ongoing project to develop response criteria for GCA, a 4-round web-based Delphi exercise was conducted. Participants included patients with GCA and health professionals with expertise in GCA. Participants rated the importance (1=lowest, 9=highest) of 51 items selected based on a systematic literature review, grouped into six domains, and could suggest additional items. Items scored 7-9 by at least 70% of health professionals and 70% of patients were considered critically important and to have reached consensus. In the last round of the Delphi, participants ranked the top 10 most relevant items. A task force (n = 32 members) meeting followed to review the Delphi results, discuss rankings, and finalize the selection of items. One hundred eighty-seven physicians and 85 patients, from 38 countries, participated in the Delphi exercise. Twenty-four (75%) task force members participated in the virtual meeting. Thirteen new items were proposed in round 1. Twenty-four items were rated as critically important. No items were excluded during any round, and consensus was not reached for 40 items. The top 3 highest rated items by both patients and physicians were headache (ranked highest by 52%), amaurosis fugax (highest=10%), and jaw claudication (highest=7%). Twelve items were selected for the next phase of the project. Experts and patients identified 12 items considered important for measuring response to treatment in GCA.