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Objective: To assess the role of cardiovascular risk factors, measured at the time of diagnosis, in the pathogenesis of giant cell (temporal) arteritis (GCA)., Methods: Four hundred new patients with GCA or polymyalgia rheumatica (PMR) and population-based, individually age- and sex-matched controls were included in this multicenter, prospective case-control study. Each participant was evaluated by review of the medical history and by clinical and laboratory assessments., Results: Among women, smoking was associated with a 6-fold increase in risk (P = 0.00006, 95% confidence interval [95% CI] 2-17), heavy smoking with a 17-fold increase in risk, and previous atheromatous disease with a 4.5-fold increase in risk (P = 0.0003, 95% CI 2-11) of GCA in both the biopsy-positive and biopsy-negative GCA groups; only smoking appeared to be a risk factor for PMR in women (odds ratio 3.64, 95% CI 1.07-12.40). Among men, no risk factor was found to be significant., Conclusion: Smoking and previous arterial disease were independently associated with GCA in women. In order to avoid matching bias, risk factors for diseases with an unbalanced sex distribution should be studied separately in each sex, using a sex-matched, case-control study design.

Objective: To assess the prevalence and thrombogenic role of anticardiolipin antibodies (aCL) in giant cell arteritis., Methods: Two hundred eighty-four patients with newly diagnosed temporal arteritis or polymyalgia rheumatica and 210 age- and sex-matched controls randomly selected from the general population were included in a multicenter, prospective case-control study. Blood samples were obtained at the time of diagnosis, data on initial clinical features were collected in a questionnaire, and temporal artery biopsy findings were reviewed by an experienced pathologist., Results: Anticardiolipin antibodies were present in 20.7% of patients compared with 2.9% of controls (P = 1.45 x 10(-9)). The prevalence of aCL was higher in samples found positive for temporal arteritis than in those found negative on biopsy (31.2% versus 16.7%; P = 0.04), and was similarly higher in the biopsy-positive temporal arteritis group compared with the polymyalgia rheumatica and control groups. Although aCL were associated with thrombotic complications in univariate analysis, the positivity of the biopsy findings remained the only predictive variable in stratified analysis., Conclusion: In giant cell arteritis, aCL seem to function as reactive antibodies in relation to endothelial lesions.