Hyeok Choi1, Youhyun Kim1, Seung Min Jung2, Jason Jungsik Song2,3, Yong-Beom Park2,3, Sang-Won Lee4,5. 1. Department of Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea. 2. Division of Rheumatology, Department of Internal Medicine, Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea. 3. Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea. 4. Division of Rheumatology, Department of Internal Medicine, Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea. sangwonlee@yuhs.ac. 5. Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea. sangwonlee@yuhs.ac.
Abstract
OBJECTIVES: We investigated whether low serum C3 level can cross-sectionally estimate severe antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in immunosuppressive drug-naïve patients at diagnosis. METHODS: We retrospectively reviewed the medical records of 139 patients with AAV, who were first classified as AAV at Severance Hospital. We obtained clinical and laboratory data including serum complement 3 (C3) level and calculated Birmingham vasculitis activity score (BVAS) at diagnosis. We stratified AAV patients into three groups according to the tertile of BVAS and defined the lower limit of the highest tertile as the cutoff for severe AAV (BVAS at diagnosis ≥ 16) at diagnosis. Low serum C3 level was defined as C3 < 90 mg/dL. The odds ratio (OR) was assessed using the multivariable logistic regression. RESULTS: The mean age at diagnosis was 56.3 years and 41 patients were men (29.5%). The mean initial BVAS was 12.8. The mean serum C3 and C4 levels were 110.6 and 26.8 mg/dL. Thirty-one patients (22.3%) exhibited low serum C3 level at diagnosis. In the multivariable analysis, serum C3 level at diagnosis < 90 mg/dL (OR 2.963) exhibited the significant association with severe AAV at diagnosis. Patients with low serum C3 level exhibited a significantly high relative risk (RR) for severe AAV at diagnosis compared to those without (RR 3.600). Patients with low serum C3 level at diagnosis exhibited poor renal prognosis than those without. CONCLUSION: Low serum C3 level can estimate severe AAV and predict poor renal outcome in immunosuppressive drug-naïve patients at diagnosis.
OBJECTIVES: We investigated whether low serum C3 level can cross-sectionally estimate severe antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in immunosuppressive drug-naïve patients at diagnosis. METHODS: We retrospectively reviewed the medical records of 139 patients with AAV, who were first classified as AAV at Severance Hospital. We obtained clinical and laboratory data including serum complement 3 (C3) level and calculated Birmingham vasculitis activity score (BVAS) at diagnosis. We stratified AAV patients into three groups according to the tertile of BVAS and defined the lower limit of the highest tertile as the cutoff for severe AAV (BVAS at diagnosis ≥ 16) at diagnosis. Low serum C3 level was defined as C3 < 90 mg/dL. The odds ratio (OR) was assessed using the multivariable logistic regression. RESULTS: The mean age at diagnosis was 56.3 years and 41 patients were men (29.5%). The mean initial BVAS was 12.8. The mean serum C3 and C4 levels were 110.6 and 26.8 mg/dL. Thirty-one patients (22.3%) exhibited low serum C3 level at diagnosis. In the multivariable analysis, serum C3 level at diagnosis < 90 mg/dL (OR 2.963) exhibited the significant association with severe AAV at diagnosis. Patients with low serum C3 level exhibited a significantly high relative risk (RR) for severe AAV at diagnosis compared to those without (RR 3.600). Patients with low serum C3 level at diagnosis exhibited poor renal prognosis than those without. CONCLUSION: Low serum C3 level can estimate severe AAV and predict poor renal outcome in immunosuppressive drug-naïve patients at diagnosis.