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.