Giant cell arteritis (GCA) is described as a ‘do not miss’ diagnosis in that any delays can lead to loss of vision.
According to a new systematic review, researchers from the Department of Rheumatology and Clinical Immunology, University of Groningen, found that a combination of clinical laboratory markers provides the most accurate way of diagnosing GCA.
They identified a total of 68 studies including 14,037 patients and calculated positive likelihood ratios (PLRs), that is, higher values indicate a higher probability that a factor increasing the risk of a disease, for a range of clinical symptoms and laboratory markers.
The results showed that significant clinical symptoms which, if present, should upgrade the level of suspicion for GCA were limb (PLR = 6.01) and jaw (PLR = 4.90) claudication, temporal artery thickening (PLR = 4.70) and temporal artery loss of pulse (PLR = 3.25). Significant laboratory markers included a platelet count of greater than 400 x 103/micro/litre (PLR = 3.75), erythrocyte sedimentation rates (ESR) of greater than 100mm/h (PLR = 3.11). In contrast, significant negative likelihood ratios included patients aged less than 70 years (LR = 0.48) and the absence of a C-reactive protein level of 2.5mg/dl or more (LR = 0.38).
The authors concluded that their study had identified the key clinical and laboratory markers which should be assessed when there was a suspicion of GCA.
Van der Geest KSM et al. Diagnostic accuracy of symptoms, physical signs, and laboratory tests for giant cell arteritis: A systematic review and meta-analysis. JAMA Intern Med 2020; August 17, 2020. doi:10.1001/jamainternmed.2020.3050