Is Erythrocyte Sedimentation Rate Necessary for the Initial Diagnosis of Giant Cell Arteritis?

Abstract

Giant cell arteritis (GCA) is an ophthalmological emergency that can be difficult to diagnose and prompt treatment is vital. We investigated the sequential diagnostic value for patients with suspected GCA using three biochemical measures as they arrive to the clinician: first, platelet count, then C-reactive protein (CRP), and lastly, erythrocyte sedimentation rate (ESR). This retrospective cross-sectional study of consecutive patients with suspected GCA investigated platelet count, CRP, and ESR using diagnostic test accuracy statistics and odds ratios (ORs) in a sequential fashion. The diagnosis was established by experts at follow-up, considering clinical findings and tests including temporal artery biopsy. A total of 94 patients were included, of which 37 (40%) were diagnosed with GCA. Compared with those without GCA, patients with GCA had a higher platelet count (p < 0.001), CRP (p < 0.001), and ESR (p < 0.001). Platelet count demonstrated a low sensitivity (38%) and high specificity (88%); CRP, a high sensitivity (86%) and low specificity (56%); routine ESR, a high sensitivity (89%) and low specificity (47%); and age-adjusted ESR, a moderate sensitivity (65%) and moderate specificity (65%). Sequential analysis revealed that ESR did not provide additional value in evaluating risk of GCA. Initial biochemical evaluation can be based on platelet count and CRP, without waiting for ESR, which allows faster initial decision-making in GCA.

The spectrum of giant cell arteritis through a rheumatology lens

“…Laboratory markers of inflammation (acute phase markers) may be rapidly normalised by glucocorticoid therapy; typically, both ESR and CRP are raised but it is worth taking a blood sample for both markers prior to starting glucocorticoids. In the event of conflicting results, CRP tends to be more reliable [28] as ESR may be elevated by unrelated conditions such as monoclonal gammopathy. However, if CRP is only slightly elevated above the reference range, a clearly-elevated ESR can be a useful clue to inflammatory disease.…”