HOW DOES PREVIOUS CORTICOSTEROID TREATMENT AFFECT THE BIOPSY FINDINGSIN GIANT-CELL (TEMPORAL) ARTERITIS

Objective: To determine the effect of previous corticosteroid treatmen t on the results of temporal artery biopsy. Design: Consecutive case s eries. Setting: Tertiary care center. Patients: A consecutive cohort o f 535 patients who had temporal artery biopsies at Mayo Clinic, Roches ter, Minnesota, between 1 January 1988 and 31 December 1991. Measureme nts and Results: The dose and duration of corticosteroid treatment rec eived before temporal artery biopsy and detailed clinical and laborato ry data were obtained from the patients' medical records. All temporal artery biopsy slides were re-evaluated by a pathologist blinded to cl inical data, previous corticosteroid treatment information, and the or iginal pathologic diagnosis. Biopsy specimens were classified as negat ive for arteritis, positive for typical temporal arteritis, or positiv e for atypical temporal arteritis. Biopsy results were positive for 31 % of patients (89 of 286) who did not receive corticosteroids before b iopsy and for 35% of those (86 of 249) who did receive corticosteroids before biopsy (P = 0.4; 95% confidence interval for the difference, - 4.7% to 11.5%). Patients who received corticosteroids before biopsy te nded to have clinical features more suggestive of arteritis. A multipl e logistic regression analysis model, controlling for these difference s in clinical and laboratory features, showed that the biopsy positivi ty rate was unrelated to previous corticosteroid treatment. Conclusion s: Although these results do not prove that histologic features are un affected by corticosteroids, they show that, in this large, consecutiv e sample, the positivity rates of temporal artery biopsy were similar in untreated and corticosteroid-treated patients. Temporal artery biop sy may show arteritis even after more than 14 days of corticosteroid t herapy in the presence of clinical indications of active disease.