Understanding Referral and Diagnostic Pathways for Giant Cell Arteritis
Bibliographic record
Abstract
Objectives Giant cell arteritis (GCA) is considered a rheumatologic emergency due to early risks of vision loss and stroke. At our center, there is currently no standard pathway for referral or diagnostic testing of GCA, which may result in diagnostic delays and/or unnecessary exposure to prednisone. The aim of this study was to better understand the pathways followed by patients referred for suspected GCA to identify barriers to care and areas for improvement. Methods Charts of patients referred to University of Alberta Rheumatology for query GCA between January 2022 and January 2024 were retrospectively reviewed. Second opinions and transfer of care referrals were excluded. Patient demographics, number of days between referral and first Rheumatology visit, types of diagnostic tests ordered (imaging, labs, biopsies), time to confirmation/exclusion of diagnosis of GCA (days) and cumulative exposure to prednisone until diagnosis determined (mg) were recorded. Data was analyzed using descriptive statistics. Results Of 779 patients with a triage diagnosis of vasculitis or polymyalgia rheumatica, 81 new referrals for query GCA were identified. Of these 81, 60 (74.1%) were women and mean age was 72.1 (±10.3) years. Most were referred by family medicine (36, 44.4%), ophthalmology (14, 17.3%), and emergency medicine (14, 17.3%). The median time between referral and first rheumatology visit was 9 (0-113) days. The most frequently ordered diagnostic test was temporal artery biopsy (66, 81% of patients), followed by PET scan (32, 39.5%), and temporal artery ultrasound (3, 3.7%). Ultimately, a diagnosis of GCA was made in 53 (65.4%) of referred patients [confirmed by either biopsy or imaging in 38 (47%) or clinically diagnosed in the absence of a positive test in 15 (18.5%)] and excluded in 28 (34.6%). The median time between Rheumatology referral to the result of first confirmatory test was 13 (3-529) days, and median time to exclusion of GCA diagnosis was 25 (0-189) days. Ultimately, 66 (81%) patients received prednisone while work-up was performed, with side effects reported in 42 (63.6%). The median cumulative prednisone exposure to those in whom GCA was ultimately excluded was 785 (0-4890) mg. Conclusion Of patients referred to rheumatology for suspected GCA, the diagnosis was confirmed by testing in 47%, made clinically in 18%, and excluded in 35%. There was wide variability in time to confirmation/exclusion of diagnosis, during which patients received large amounts of prednisone. These findings indicate the need for a standard referral/diagnostic pathway to expedite testing and reduce unnecessary exposure to high dose prednisone.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.015 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".