Value of temporal artery biopsy length in diagnosing giant cell arteritis.

Giant cell arteritis (GCA) is considered an ophthalmological emergency with severe sight and life-threatening sequelae. Temporal artery biopsy (TAB) is the current gold standard for the diagnosis of GCA; however, the required length of biopsy remains an issue of contention in the literature.,Retrospective case-control study of a consecutive cohort of 545 patients who had undergone TABs across five hospitals between 1 January 1992 and 1 January 2016. In patients with either positive or negative TABs, we collected age, sex, biopsy length and erythrocyte sedimentation rate (ESR).,A total of 538 patients were included in the final analysis. Of these, 23.4% of TABs were positive, with the average length being 17.6 mm. There was a significant difference in means for positive (19.9 mm) and negative (16.8 mm) biopsies (P = 0.0009). Each millimetre increase in TAB length increased the odds of a positive TAB by 3.4% (P = 0.024). A cut-off point of ≥15 mm increased the odds of a positive TAB by 2.25 compared with a TAB <15 mm (P = 0.003). We also found that ESR ≥50 mm/h was a very strong predictor for a positive TAB result (P < 0.0001).,Biopsy length and ESR were significant predictors of a pathological diagnosis of GCA. We also found that the optimal length threshold predictive for GCA was 15 mm in order to avoid a false-negative GCA diagnosis. Although TAB remains the gold standard for diagnosis, clinicians should refer to both clinical and pathological data to guide their management.