Background/Purpose: Temporal arteritis or giant cell arteritis (GCA) is a large vessel vasculitis that involves extracranial arteries. The historical gold standard for diagnosis is a temporal artery biopsy (TAB) which has potential for false negativity. Current guidelines recommend biopsy lengths of at least one cm with no suggestion of an upper limit. The purpose of this study is to review all biopsy lengths performed in the province of Alberta, Canada to identify an ideal biopsy length as well as other predictors of a positive diagnosis of GCA.

Methods: A retrospective chart review was performed on patients who had undergone a TAB procedure in 22 sites between January 1^st, 2008 to January 1^st, 2018.Data extracted included patient’s age sex, levels of inflammatory markers (ESR and CRP), side of biopsy, post-fixation length and final pathological diagnoses. Predictors of positive pathology were modelled using logistic regression. Stata 14.1 (StataCorp) was used for data analysis.

Results: A total of 1203 biopsies were identified over the decade. Median age was 73 (quartile range [QR], 64–80) years, with 806 (67%) female patients. A total of 235 (20%) biopsies were diagnosed as GCA, with median biopsy length of 1.3 cm (QR, 0.9–1.8 cm). Biopsy lengths between sites ranged between 0.8 cm (QR, 0.6–1.1 cm) to 2.2 cm (QR, 1.5–3.3 cm). Univariate analysis noted increased age (odds ratio [OR] 1.04 per year, 95% CI, 1.02–1.05; p < 0.001), ESR (OR 1.01 per unit, 95% CI, 1.01–1.02; p < 0.001), CRP (OR 1.01 per unit, 95% CI, 1.01–1.01; p < 0.001) and biopsy lengths (OR 1.25 per cm, 95% CI, 1.06–1.46; p = 0.007) were associated with positive GCA diagnosis. In multivariate analysis, only age (OR 1.04 per year, 95% CI, 1.02–1.05; p < 0.001) and CRP (OR 1.01 per unit, 95% CI, 1.00-1.01; p < 0.001) remained statistically significant predictors of a positive GCA diagnosis. We noted an increasing odds ratio for a positive biopsy with increasing length of biopsy up until 2.00–2.49 cm (OR 2.79 per cm 95% CI, 1.10 – 7.09).

Conclusion: This study indicates the optimal upper end of temporal artery biopsy length is between 2.00-2.49 cm. We note the highest OR of a positive biopsy is associated with biopsies of this length, with longer biopsies not providing additional diagnostic yield to justify risks. Our study also shows that age, ESR, CRP and TAB length were significant independent predictors of pathological diagnosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-ten-year-retrospective-review-of-temporal-artery-biopsy-lengths-in-alberta/