Objective: To assess whether the intensity of the initial systemic inflammatory response is able to predict response to therapy in patients with giant cell arteritis (GCA).
Methods: Retrospective review of 75 patients (49 women and 26 men) with biopsy-proven GCA who had regular followup and were treated according to uniform criteria. Four parameters were used to evaluate the baseline inflammatory response at diagnosis: fever, weight loss, erythrocyte sedimentation rate > or = 85 mm/hour, and hemoglobin < 110 gm/liter. Patients were considered to have a weak inflammatory response if they had 2 or fewer inflammatory parameters (group 1) and a strong inflammatory response if 3 or 4 parameters were present (group 2). Time required to achieve a maintenance dose of less than 10 mg prednisone/day was recorded and analyzed by the Kaplan-Meier survival analysis method. Tumor necrosis factor alpha (TNFalpha) and interleukin 6 (IL-6) serum levels were also determined in 62 patients and 15 controls.
Results: Forty patients had a weak (group 1) and 35 had a strong (group 2) initial inflammatory response. Patients in group 2 had significantly higher levels of circulating TNFalpha (31.9 +/- 16.8 versus 22.3 +/- 9 pg/ml; P = 0.01) and IL-6 (28.2 +/- 17.4 versus 16.6 +/- 13 pg/ml; P = 0.004) than patients in group 1. In group 1, 50% of patients required a median of 40 weeks (95% CI 37-43) to reach a maintenance dose of <10 mg, whereas in group 2 a median of 62 weeks (95% CI 42-82) was necessary (P = 0.0062). Patients in group 2 experienced more flares than patients in group 1 (P = 0.01) and received higher cumulative steroid doses (8.974 +/- 3.939 gm versus 6.893 +/- 3.075 gm; P = 0.01).
Conclusion: GCA patients with a strong initial systemic inflammatory reaction have more elevated circulating levels of IL-6 and TNFalpha, have higher and more prolonged corticosteroid requirements, and experience more disease flares during corticosteroid therapy than patients with a weak systemic acute phase response.