Risk factors for visual loss in giant cell (Temporal) arteritis: A prospective study of 174 patients

OBJECTIVE: To determine the risk factors-especially the effects of thromboc ytosis-for permanent visual loss in patients with temporal arteritis. METHODS: One hundred seventy-four patients with temporal arteritis (147 bio psy proven) were prospectively observed for the development of permanent vi sual loss. We used multivariate logistic regression analysis to determine w hich of 17 pretreatment characteristics were associated with visual loss. RESULTS: Visual ischemic manifestations occurred in 48 (28%) patients, incl uding permanent visual loss in 23 (13%) patients. The independent predictor s associated with an increased risk of permanent visual loss were a history of transient visual ischemic symptoms (odds ratio [OR] = 6.3; 95% confiden ce interval [CI]: 1.4 to 29; P = 0.02) and a higher platelet count (OR = 3. 7 per SD; 95% CI: 1.8 to 7.9; P = 0.001). The presence of constitutional sy mptoms (OR = 0.14; 95% CI: 0.02 to 0.77, P = 0.01), polymyalgia rheumatica (OR = 0.04; 95% CI: 0.01 to 0.48, P = 0.02), and C-reactive protein level ( OR = 0.35 per SD; 95% Cl: 0.13 to 0.92, P = 0.03) were associated with a re duced risk. Upper limb artery involvement was excluded from the multivariat e model, as no patients with that problem developed permanent visual loss. Of the 87 patients who presented with thrombocytosis (platelet count > 400 X 10(9)/L), 32 (37%) developed ischemic visual symptoms, compared with 16 ( 18%) of those without thrombocytosis. CONCLUSIONS: An elevated platelet count is a risk factor for permanent visu al loss in temporal arteritis. The finding of thrombocytosis in a patient w ith suspected temporal arteritis should emphasize the need for urgent treat ment, with consideration of using inhibitors of platelet aggregation or ant icoagulation therapy. (C) 2001 by Excerpta Medica, Inc.