Background/Purpose: TAB is currently considered the gold standard for the diagnosis of GCA. However, it is suspected that the sensitivity of TAB is limited by the segmental nature of the artery involvement in this condition. Expert opinion for obtaining TAB recommends an initial unilateral approach with an attempt to obtain at least 10-20 mm of artery, followed by the pursuit of the contralateral side if initial biopsy is negative and clinical suspicion remains high. Several smaller retrospective studies have not reached a consensus with regards to the optimal length of TAB. This study aimed to determine if length of TAB or initial bilateral TAB impacted the yield of positive TAB result in the national VHA cohort.

Methods: Subjects with a procedure code for TAB between 1999-2017 were queried through the VHA national database. TAB reports (positive, negative) were reviewed manually; indeterminate results (i.e. inconclusive, healed arteritis) were categorized as negative. The following data was extracted: 1) post-fixation TAB length 2) whether bilateral TAB was performed in one sitting 3) age at TAB 4) gender. TAB length categories were organized as follows: ≤10 mm, 10 to ≤15 mm, 15 to ≤20 mm, 20 to ≤25 mm, 25 to ≤30 mm, and ≥30 mm. Multivariate analyses and logistic regression models were run using Stata.

Results: A total of 3,057 biopsies were reviewed; 306 (10%) were deemed positive per pathology report. The likelihood of a positive TAB significantly correlated with TAB length greater than 30 mm (OR 1.65, CI 1.06-2.57, p<0.05 when compared to a reference category ≤10 mm) as well as with bilateral biopsy in one sitting (OR 2.05, CI 1.43-2.94, p<0.01), suggesting higher yield with longer or initial bilateral biopsies. The likelihood of a positive TAB was incrementally higher with longer biopsies. Positive TAB also significantly correlated with age greater than 70 years (OR 1.9 in the age 61-70 group, CI 1.0-3.7, p=0.07; OR 4.2 in the age 71-80 group, CI 2.2-8.3, p<0.01; OR 6.0 in the age ≥80 group, CI 3.1-11.6, p<0.01 when compared to a reference category aged 51-60 years). Neither gender or age influenced TAB length or the likelihood that bilateral TAB was performed.

Conclusion: This is the largest retrospective study to date examining the relationship between TAB length and yield. Longer length of biopsy (≥30 mm) was more likely to yield a positive TAB. Additionally, initial bilateral TAB was twice as likely to yield a positive result compared with unilateral TAB. These observations may be explained by “skip lesions” that can lead to false-negative results with shorter TAB. Overall, these findings suggest that higher yield of TAB might be achieved with longer or initial bilateral biopsies.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-longer-or-bilateral-temporal-artery-biopsy-tab-is-more-likely-to-yield-a-positive-result-for-giant-cell-arteritis-gca-in-the-veterans-health-administration-vha-database-cohort/