Temporal artery biopsy ... Who needs one?

Objective: To review a 10 year period of temporal artery biopsies, using the American College of Rheumatology (ACR) 1990 criteria: a five point scoring system for the diagnosis of giant cell arteritis (GCA). Design: Population based, retrospective cohort analysis. Setting: One district general hospital in the United Kingdom, over one decade. Participants: All patients who underwent temporal artery biopsy from July 1994 to June 2004. Main outcome measures: ACR score and temporal artery biopsy result. Results: During the 10 year period 111 patients were identified. The median ( range) age at presentation was 71 ( 29 - 85) years. Seventy five patients had an initial ACR score of three or four at presentation. There were 20 positive biopsy specimens. In 19 of these cases at least three of the other criteria were positive so there was already sufficient clinical information for a confident diagnosis. In only one case did the positive result influence the diagnosis by changing the ACR score from two to three. In our series, corticosteroid treatment before biopsy did not significantly reduce the yield of the biopsy. Conclusions: The ACR score of three or more has a sensitivity of 93.5% and specificity of 91.2% for the diagnosis of GCA. Using these criteria, 68% of patients had sufficient clinical features when referred to make a confident diagnosis of GCA. Temporal artery biopsy was therefore unnecessary in this group. In the remaining group ( ACR score ( 2) there was one positive biopsy. The biopsy only changed the diagnosis in this one case - less than 3% of the uncertain cases and less than 1% of the total cases. Using the ACR criteria and restricting biopsy to those cases in which it might change the diagnosis will reduce the number of biopsies by two thirds without jeopardising diagnostic accuracy.