Objective We investigated the ability of known clinical signs and symptoms, as well as common laboratory tests, to correctly predict a positive temporal artery biopsy. Design A prospective cohort study. Participants Consecutive patients in a tertiary referral centre undergoing temporal artery biopsy. Methods Clinical information was collected using a predesigned questionnaire. Pathology results and laboratory information were collected from digital patient records. Main Outcome measure The predictive value of clinical signs, symptoms, and laboratory values of a positive temporal artery biopsy. Results Over a 3-year period, 259 patients were enrolled and 251 patients were analyzed. Sixty-one patients had a positive biopsy. Clinical features most predictive of a positive biopsy were jaw claudication (positive likelihood ratio [LR+] 2.31) and abnormal temporal artery pulse (LR+ 2.62). Receiver operating characteristic curves generated for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and platelets values showed an area under curve (AUC) value of 0.71, 0.75, and 0.76, respectively. The initiation of steroids decreased the diagnostic utility of the ESR, CRP, and platelets values (AUC = 0.58, 0.61, and 0.63, respectively). Conclusions A variety of clinical signs and symptoms were observed in patients referred for a temporal artery biopsy. Clinical signs and symptoms were less accurate in predicting a positive biopsy than laboratory tests. No combination of clinical signs and symptoms tested was able to predict giant cell arteritis with the certainty necessary to justify or withhold long-term steroid therapy.
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