Ponte, CristinaGrayson, Peter C.Robson, Joanna C.Suppiah, RaviGribbons, Katherine BatesJudge, AndrewCraven, AntheaKhalid, SaraHutchings, AndrewWatts, Richard A.Merkel, Peter A.Luqmani, Raashid A.2022-11-222022-11-222022Ann Rheum Dis. 2022 Dec;81(12):1647-16530003-4967http://hdl.handle.net/10451/55197© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.Objective: To develop and validate updated classification criteria for giant cell arteritis (GCA). Methods: Patients with vasculitis or comparator diseases were recruited into an international cohort. The study proceeded in six phases: (1) identification of candidate items, (2) prospective collection of candidate items present at the time of diagnosis, (3) expert panel review of cases, (4) data-driven reduction of candidate items, (5) derivation of a points-based risk classification score in a development data set and (6) validation in an independent data set. Results: The development data set consisted of 518 cases of GCA and 536 comparators. The validation data set consisted of 238 cases of GCA and 213 comparators. Age ≥50 years at diagnosis was an absolute requirement for classification. The final criteria items and weights were as follows: positive temporal artery biopsy or temporal artery halo sign on ultrasound (+5); erythrocyte sedimentation rate ≥50 mm/hour or C reactive protein ≥10 mg/L (+3); sudden visual loss (+3); morning stiffness in shoulders or neck, jaw or tongue claudication, new temporal headache, scalp tenderness, temporal artery abnormality on vascular examination, bilateral axillary involvement on imaging and fluorodeoxyglucose-positron emission tomography activity throughout the aorta (+2 each). A patient could be classified as having GCA with a cumulative score of ≥6 points. When these criteria were tested in the validation data set, the model area under the curve was 0.91 (95% CI 0.88 to 0.94) with a sensitivity of 87.0% (95% CI 82.0% to 91.0%) and specificity of 94.8% (95% CI 91.0% to 97.4%). Conclusion: The 2022 American College of Rheumatology/EULAR GCA classification criteria are now validated for use in clinical research.engGiant cell arteritisMagnetic resonance imagingSystemic vasculitis.journal article10.1136/ard-2022-2234801468-2060