Low serum complement 3 level is associated with severe ANCA-associated vasculitis at diagnosis
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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.
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.
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.
Low serum C3 level can estimate severe AAV and predict poor renal outcome in immunosuppressive drug-naïve patients at diagnosis.
KeywordsAntineutrophil cytoplasmic antibody-associated vasculitis Complement 3 Severity Renal outcome
All authors contributed to the study concept, design, acquisition, and interpretation of data. HC, YHK, and SWL performed the statistical analysis. HC, YHK, YBP, and SWL drafted and revised manuscript. All authors have read and approved the manuscript for publication.
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2017R1D1A1B03029050) and a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (HI14C1324).
Compliance with ethical standards
Conflict of interest
The authors declare no competing interests.
This study was approved by the institutional Review Board of Severance Hospital (4-2017-0673).
The patient’s written informed consent was waived by the approving IRB, as this was a retrospective study.
- 7.Jennette JC, Falk RJ, Hu P, Xiao H. Pathogenesis of antineutrophil cytoplasmic autoantibody-associated small-vessel vasculitis. Annu Rev Pathol. 2013;24:8:139–60. https://doi.org/10.1146/annurev-pathol-011811-132453.CrossRefGoogle Scholar
- 15.Stone JH, Hoffman GS, Merkel PA, et al. A disease-specific activity index for Wegener’s granulomatosis: modification of the Birmingham vasculitis activity score. International Network for the Study of the Systemic Vasculitides (INSSYS). Arthritis Rheum. 2001;44(4):912–20. https://doi.org/10.1002/1529-0131(200104)44:4%3C912::AID-ANR148%3E3.0.CO;2-5.CrossRefGoogle Scholar