AB0537 DIAGNOSTIC ACCURACY OF SYMPTOMS AND SIGNS FOR GIANT CELL ARTERITIS: SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract

Background:Making a correct diagnosis of giant cell arteritis (GCA) is critical given the potential complications of the disease and its therapy. Estimation of the clinical probability of GCA is challenging. Prediction models might be helpful, but have methodological and practical draw backs. One earlier meta-analysis described the diagnostic accuracy of symptoms and signs for a positive temporal artery biopsy [1]. In the latter study, the diagnostic accuracy of symptoms and signs might have been overestimated due to inclusion of case-control studies.Objectives:To evaluate the diagnostic accuracy of symptoms and signs for GCA.Methods:PubMed, EMBASE and the Cochrane Database were searched for relevant studies. Studies were eligible if: all patients were suspected of having GCA; either a temporal artery biopsy (TAB), imaging test, or clinical diagnosis was used as reference standard for GCA; a 2x2 table was available for at least one symptom, physical sign or routine laboratory test (i.e. the index tests). Case reports and case-control studies were excluded. The screening, full text review, quality assessment with QUADAS-2 tool and data extraction were performed by two investigators. Hierarchical logistic regression modelling provided the pooled estimates of likelihood ratios with their 95% confidence intervals. Likelihood ratios <0.5 (i.e. making GCA less likely) or >2.0 (i.e. making GCA more likely) were considered diagnostically relevant.Results:Out of 1359 reports screened, 59 studies were included in the study. These reports contained 13406 patients, including 3940 GCA patients. Most studies were retrospective, performed at tertiary centres and published after the prior meta-analysis [1]. TAB was the reference standard in 36 studies and a clinical diagnosis in 23 studies. Quality assessment revealed substantial risk of selection bias in the majority of studies. Studies using a clinical diagnosis were at risk of bias, as the reference standard might be influenced by the index tests (e.g. symptoms). Jaw claudication, limb claudication, temporal tenderness, temporal artery abnormalities, especially arterial thickening or loss of pulse, and anterior ischemic optic neuropathy provided a positive likelihood ratio >2.0. None of the 19 symptoms and 7 physical signs evaluated, provided a negative likelihood ratio <0.5. An ESR >60mm/hr and platelet count >400*109/L provided a positive likelihood ratio of >2.0. Absence of an elevated CRP level or ESR >60mm/hr yielded a negative likelihood ratio of <0.5. Studies using a clinical diagnosis as reference standard reported higher positive likelihood ratios for jaw claudication, weight loss and PMR when compared to TAB studies. Absence of an elevated CRP provided a lower negative likelihood ratio in studies using the clinical diagnosis.Conclusion:Few clinical findings may help to estimate the clinical probability of GCA. The presence or absence of any particular symptom or sign does not sufficiently rule out or rule in GCA. These findings highlight the need of additional tests (i.e. imaging, biopsy) in patients suspected of having GCA.