THU0455 Age is more closely associated with positive temporal artery biopsy over biopsy length in large veterans administration database study
Authors: M.B. Morcos, S. Chung, B. Ng
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Giant cell arteritis (GCA) is a granulomatous vasculitis with a predilection for older women. While American College of Rheumatology (ACR) diagnostic guidelines exist, temporal artery biopsy (TAB) remains an essential tool often used independently to substantiate long-term steroid use and/or immunosuppression. No consensus exists regarding the ideal length of biopsy to optimise pathological yield. The influence of demographic factors such as age, race, and gender on the yield of biopsies is not defined. <h3>Objectives</h3> To determine if length of TAB and patient's race, gender, or age at biopsy influenced TAB results using the Veteran's Administration (VA) national database. <h3>Methods</h3> Patients with a procedure code for TAB between 1999–2017 were queried through the VA national database. The biopsy length and result (positive, negative, or indeterminate) were recorded. Demographic information including subject age, gender, and race was also extracted. Logistic regression models were run using Stata to identify independent determinants of a positive TAB. <h3>Results</h3> 2136 biopsies have been randomly reviewed to date. The average length of TAB was 12.15 mm. TAB results were 9% positive, 89% negative, and 2% indeterminate. There was no statistically significant association between biopsy length and a positive result; however, when compared to the reference group (&gt;10 mm-&lt;15 mm), the odds ratio for positive results increased with specimen length &gt;20 mm to 30 mm in length. Conversely, there was a trend towards negative biopsy results for samples&lt;10 mm in length when compared to the reference length group. There was no correlation between TAB result and race or gender; however, age correlated with a positive biopsy which was statistically significant. None of the subjects&lt;50 years of age had a positive TAB. Younger age groups (age categories 50–59 and 60–69) were less likely to have a positive TAB (OR of 0.32 CI 0.17–0.61 and OR 0.53 CI 0.38–0.74, respectively) when compared to the reference age group (age 70–79). Conversely, older populations aged 90 and above demonstrated a statistically significant increased likelihood of a positive biopsy result with an OR of 2.25, CI 1.05–4.85. <h3>Conclusions</h3> The incidence of positive TAB among patients with suspected temporal arteritis in the VA national database was surprisingly low. The effect of other factors, such as the referring specialty or pre-biopsy steroid use, on TAB result may be insightful in understanding the low yield. Age remains a helpful tool given its association with increased likelihood of a positive biopsy, and the decision to pursue TAB in patients&lt;50 years old should be approached judiciously. Length of biopsy was not associated with a positive result; however, the trends we note suggest a biopsy between 10 mm and 25 mm could optimise the yield. Gender and race were not helpful predictors for biopsy yield in this population. <h3>Disclosure of Interest</h3> None declared