Utilization of the Revised American College of Rheumatology (rACR) Scoring to Avoid Unnecessary Temporal Artery Biopsies-A Case Series

Introduction: The American College of Rheumatology (ACR) criteria, and more recently the revised ACR criteria (rACR), are a scoring system developed to aid in the diagnosis of giant cell arteritis (GCA). Our aim was to investigate the value of the non-biopsy criteria of the original ACR criteria and rACR criteria to predict GCA, and investigate the utilization of such scores to avoid biopsy when a very high or very low likelihood of a positive temporal artery biopsy TAB was predicted. Method: We conducted a retrospective cohort study of 59 patients undergoing TAB from 2013 to 2017 in Beaumont Hospital, a tertiary referral centre in Dublin, Ireland. Demographic data, biochemical results, presenting features, and histology results were collected and collated. Results: Data were analysed from 53 patients and ACR scores were compiled. Seventeen scored < 3 and thirty-six scored 3-5. All 11 positive biopsies were in the 3-5 score range. Forty-five patients were analysed with rACR scores. Eight were excluded due to not meeting the inclusion criteria. Of the 11 positive biopsies, 2 were in the 3-4 score range, and 9 were in the >= 5 score range. In the ACR method, 36% of all biopsies scored as low-risk pre-biopsy. In the rACR method, 84.4% of all biopsies scored in the low- and intermediate-risk group pre-biopsy and 15.6% of all biopsies scored in the high-risk group pre-biopsy. Conclusions: This study illustrates the potential value of the rACR scoring system as a useful tool to categorize patients according to risk with a view to avoiding unnecessary TAB. The data suggest that a TAB has a helpful role in low- and intermediate-risk groups but is of minimal benefit in the high-risk group.