Hyoun-Ah Kim1, Ja-Young Jeon, Jeong-Mi An, Bo-Ram Koh, Chang-Hee Suh. 1. Department of Rheumatology and BK21 Division of Cell Transformation and Restoration, Ajou University School of Medicine, San 5, Wonchon-dong, Yeongtong-gu, Suwon, South Korea 443-721.
Abstract
OBJECTIVE: C-reactive protein (CRP), S100A8/A9, and procalcitonin have been suggested as markers of infection in patients with systemic lupus erythematosus (SLE). We investigated the clinical significance of these factors for indication of infection in SLE. METHODS: Blood samples were prospectively collected from 34 patients with SLE who had bacterial infections and 39 patients with SLE who had disease flares and no evidence of infection. A second set of serum samples was collected after the infections or flares were resolved. RESULTS: CRP levels of SLE patients with infections were higher than those with flares [5.9 mg/dl (IQR 2.42, 10.53) vs 0.06 mg/dl (IQR 0.03, 0.15), p < 0.001] and decreased after the infection was resolved. S100A8/A9 and procalcitonin levels of SLE patients with infection were also higher [4.69 μg/ml (IQR 2.25, 12.07) vs 1.07 (IQR 0.49, 3.05) (p < 0.001) and 0 ng/ml (IQR 0-0.38) vs 0 (0-0) (p < 0.001), respectively]; these levels were also reduced once the infection disappeared. In the receiver-operating characteristics analysis of CRP, S100A8/A9, and procalcitonin, the area under the curve was 0.966 (95% CI 0.925-1.007), 0.732 (95% CI 0.61-0.854), and 0.667 (95% CI 0.534-0.799), respectively. CRP indicated the presence of an infection with a sensitivity of 100% and a specificity of 90%, with a cutoff value of 1.35 mg/dl. CONCLUSION: Our data suggest that CRP is the most sensitive and specific marker for diagnosing bacterial infections in SLE.
OBJECTIVE:C-reactive protein (CRP), S100A8/A9, and procalcitonin have been suggested as markers of infection in patients with systemic lupus erythematosus (SLE). We investigated the clinical significance of these factors for indication of infection in SLE. METHODS: Blood samples were prospectively collected from 34 patients with SLE who had bacterial infections and 39 patients with SLE who had disease flares and no evidence of infection. A second set of serum samples was collected after the infections or flares were resolved. RESULTS:CRP levels of SLEpatients with infections were higher than those with flares [5.9 mg/dl (IQR 2.42, 10.53) vs 0.06 mg/dl (IQR 0.03, 0.15), p < 0.001] and decreased after the infection was resolved. S100A8/A9 and procalcitonin levels of SLEpatients with infection were also higher [4.69 μg/ml (IQR 2.25, 12.07) vs 1.07 (IQR 0.49, 3.05) (p < 0.001) and 0 ng/ml (IQR 0-0.38) vs 0 (0-0) (p < 0.001), respectively]; these levels were also reduced once the infection disappeared. In the receiver-operating characteristics analysis of CRP, S100A8/A9, and procalcitonin, the area under the curve was 0.966 (95% CI 0.925-1.007), 0.732 (95% CI 0.61-0.854), and 0.667 (95% CI 0.534-0.799), respectively. CRP indicated the presence of an infection with a sensitivity of 100% and a specificity of 90%, with a cutoff value of 1.35 mg/dl. CONCLUSION: Our data suggest that CRP is the most sensitive and specific marker for diagnosing bacterial infections in SLE.