Clinical phenotype and complications of large vessel giant cell arteritis: A systematic review and meta-analysis.

BACKGROUND: Giant Cell Arteritis (GCA) is a heterogenous systemic granulomatous vasculitis involving the aorta and any of its major tributaries. Despite increased awareness of large vessel (LV) involvement, studies reporting incidence, clinical characteristics and complications of large-vessel GCA (LV-GCA) show conflicting results due to inconsistent disease definitions, differences in study methodologies and the broad spectrum of clinical presentations. The aim of this systematic literature review was to better define LV-GCA based on the available literature and identify distinguishing characteristics that may differentiate LV-GCA patients from those with limited cranial disease. METHODS: Published studies indexed in MEDLINE and EMBASE were searched from database inception to 7th May 2021. Studies were included if they presented cohort or cross-sectional data on a minimum of 25 patients with LV-GCA. Control groups were included if data was available on patients with limited cranial GCA (C-GCA). Data was quantitatively synthesised with application of a random effects meta-regression model, using Stata. RESULTS: The search yielded 3488 studies, of which 46 were included. Diagnostic criteria for LV-GCA differed between papers, but was typically dependent on imaging or histopathology. Patients with LV-GCA were generally younger at diagnosis compared to C-GCA patients (mean age difference -4.53 years), had longer delay to diagnosis (mean difference 3.03 months) and lower rates of positive temporal artery biopsy (OR: 0.52 [95% CI: 0.3, 0.91]). Fewer LV-GCA patients presented with cranial manifestations and only 53% met the 1990 ACR Classification Criteria for GCA. Vasculitis was detected most commonly in the thoracic aorta, followed by the subclavian, brachiocephalic trunk and axillary arteries. The mean cumulative prednisolone dose at 12-months was 6056.5mg for LV-GCA patients, relapse rates were similar between LV- and C-GCA patients, and 12% of deaths in LV-GCA patients could be directly attributed to an LV complication. CONCLUSION: Patients with LV-GCA have distinct disease features when compared to C-GCA, and this has implications on diagnosis, treatment strategies and surveillance of long-term sequalae.

The utility of ESR, CRP and platelets in the diagnosis of GCA.

BACKGROUND: To compare the utility of ESR, CRP and platelets for the diagnosis of GCA. METHOD: A clinical diagnosis of GCA was determined by case-note review of 270 individuals (68% female, mean age 72 years) referred to a central pathology service for a temporal artery biopsy between 2011 and 2014. The highest levels of ESR, CRP and platelets (within 2 weeks of diagnosis) were documented. Evaluation of ESR, CRP and platelets for the diagnosis of GCA were compared using Receiver Operating Characteristic Area Under the Curve (ROC-AUC), and sensitivity/specificity at optimum cut-off values. RESULTS: GCA was clinically diagnosed in 139 (67%) patients, with 81 TAB positive. The AUC estimates for ESR, CRP and platelets were comparable (0.65 vs 0.72 vs 0.72, p = 0.08). The estimated optimal cut-off levels were confirmed at 50 mm/hour for ESR, and determined as 20 mg/L for CRP and 300 × 109/L for platelets. Sensitivity estimates for these three tests were comparable (p = 0.45) and ranged between 66% for ESR and 71% for platelets. Specificity estimates were also comparable (p = 0.11) and ranged between 57% for ESR and 68% for CRP. There was only moderate agreement between the three positive tests (agreement 67%, kappa: 0.34), and when considered collectively, CRP and platelet positive tests were independent predictors of GCA (p <  0.001), but the ESR was not (p = 0.76). CONCLUSION: ESR, CRP and platelets are moderate, equivalent diagnostic tests for GCA, but may yield disparate results in individual patients. A combination of CRP and platelet tests may provide the best diagnostic utility for GCA.