Giant cell arteritis: laboratory predictors of a positive temporal artery biopsy.

Abstract

To identify laboratory predictors of a positive temporal artery biopsy. Cross-sectional study using retrospective electronic data base review. There were 3001 patients who had a temporal artery biopsy. The electronic database of a large health maintenance organization was searched for all patients who had a temporal artery biopsy performed from 1997 to 2006. Odds ratios for erythrocyte sedimentation rate, C-reactive protein (CRP), and platelet count values associated with a positive temporal artery biopsy. Four hundred fifty-nine cases of biopsy-proven giant cell arteritis were identified. The odds of a positive biopsy were 1.5 times greater with an erythrocyte sedimentation rate of 47 to 107 mm/hr, 5.3 times greater with a CRP >2.45 mg/dL, and 4.2 times greater with platelets >400,000/μL. In this largest population-based giant cell arteritis study in the United States to date, we reaffirm Hayreh's finding of the significance of a CRP level >2.45 mg/dL in predicting a positive biopsy. Our findings support the literature suggesting that CRP and thrombocytosis may be stronger predictors of positive biopsy than erythrocyte sedimentation rate. The authors have no proprietary or commercial interest in any of the materials discussed in this article.