Key clinical point: A biopsy length of 1.5-2 cm provides the optimal amount of information for greatest sensitivity in diagnosing giant cell arteritis while minimizing risks.

Major finding: A biopsy length 1.5-2 cm was associated with increased likelihood of positive biopsies (≥ 1.5 cm vs. < 1.5; odds ratio, 1.57; P = .011).

Study details: Retrospective analysis of 1,203 biopsies from 1,176 patients at 22 institutions.

Disclosures: The study received no funding. Several authors reported receiving personal fees from Hoffmann-LaRoche and serving as site primary investigators for industry-sponsored vasculitis trials.