Increase in the length of superficial temporal artery biopsy over 14 years

Background Giant cell arteritis is a systemic inflammatory vasculitis of large‐sized and medium‐sized arteries. Superficial temporal artery biopsy of at least 20 mm has traditionally been the standard length for histopathology to accurately diagnose giant cell arteritis. Recent studies suggest than a post‐fixation superficial temporal artery biopsy length of 7 to 10 mm is adequate for diagnosing giant cell arteritis. Design This is a retrospective observational study. Participants or samples The participants were all patients who underwent superficial temporal artery biopsy at Royal Prince Alfred Hospital, a large tertiary teaching hospital in Sydney, Australia, from 2008 to 2014. Methods Patients were identified using computerized hospital databases. Superficial temporal artery biopsy lengths were obtained from the histopathology reports. Main outcome measures We aimed to compare the superficial temporal artery biopsy lengths performed at a large tertiary hospital over the past 7 years, to those performed from 2000 to 2005, and to determine the frequency of diagnosis of giant cell arteritis over the two time periods. Results There was a total of 96 superficial temporal artery biopsies performed from 2008 to 2014. The superficial temporal artery biopsy mean (standard deviation) length was 16.0(7.3) mm. This represented a significant (P = 0.015) increase in mean superficial temporal artery biopsy length when compared with a previous audit performed from 2000 to 2005 where the mean (standard deviation) superficial temporal artery biopsy was 11.7(6.2) mm. Of the 96 TABs, 20 (20.8%) were positive for giant cell arteritis, compared with a giant cell arteritis positivity rate of 20.4% for the previous audit period from 2000 to 2005. Conclusion There has been a significant improvement in the length of superficial temporal artery biopsy performed at a tertiary hospital. Despite the increase in superficial temporal artery biopsy lengths, the giant cell arteritis positivity rate has remained stable.