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Urinary soluble CD163 and monocyte chemoattractant protein-1 in the identification of subtle renal flare in anti-neutrophil cytoplasmic antibody-associated vasculitis

Author information

Moran SM1, Monach PA2,3, Zgaga L4, Cuthbertson D5, Carette S6, Khalidi NA7, Koening CL8, Langford CA9, McAlear CA10, Moreland L11, Pagnoux C6, Seo P12, Specks U13, Sreih A10, Wyse J14, Ytterberg SR15, Merkel PA10,11, Little MA1,16. Nephrol Dial Transplant. 2018 Oct 31. doi: 10.1093/ndt/gfy300. [Epub ahead of print]

Abstract

Author information 1 Trinity Health Kidney Centre, Trinity College Dublin, Dublin, Ireland. 2 Section of Rheumatology, Boston University School of Medicine, Boston, MA, USA. 3 Rheumatology Section, VA Boston Healthcare System, Boston, MA, USA. 4 Department of Public Health and General Practice, Trinity College Dublin, Dublin, Ireland. 5 Department of Biostatistics and Informatics, Department of Pediatrics, University of South Florida, Tampa, FL, USA. 6 Division of Rheumatology, Mount Sinai Hospital, Toronto, ON, Canada. 7 Division of Rheumatology, St. Joseph's Healthcare, McMaster University, Hamilton, ON, Canada. 8 Division of Rheumatology, University of Utah, Salt Lake City, UT, USA. 9 Division of Rheumatology, Cleveland Clinic, Cleveland, OH, USA. 10 Division of Rheumatology, University of Pennsylvania, Philadelphia, PA, USA. 11 Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, PA, USA. 12 Division of Rheumatology, Johns Hopkins University, Baltimore, MD, USA. 13 Division of Pulmonology, Mayo Clinic College of Medicine, Rochester, MN, USA. 14 Discipline of Statistics, School of Computer Science and Statistics, Trinity College Dublin, Dublin, Ireland. 15 Division of Rheumatology, Mayo Clinic College of Medicine, Rochester, MN, USA. 16 Irish Centre for Vascular Biology, Trinity College Dublin, Dublin, Ireland.

Abstract

BACKGROUND: Prior work has shown that urinary soluble CD163 (usCD163) displays excellent biomarker characteristics for detection of active renal vasculitis using samples that included new diagnoses with highly active renal disease. This study focused on the use of usCD163 in the detection of the more clinically relevant state of mild renal flare and compared results of usCD163 testing directly to testing of urinary monocyte chemoattractant protein-1 (uMCP-1).

METHODS: Patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV, n = 88) were identified within a serially sampled, longitudinal and multicentre cohort. Creatinine-normalized usCD163 and uMCP-1 levels were measured by enzyme-linked immunosorbent assay and, both alone and in combination, were compared between times of active renal AAV and during remission and/or active non-renal AAV.

RESULTS: Samples from 320 study visits included times of active renal vasculitis (n = 39), remission (n = 233) and active extrarenal vasculitis (n = 48). Median creatinine levels were 0.9 mg/dL [interquartile range (IQR) 0.8-1.2] in remission and 1.4 mg/dL (IQR 1.0-1.8) during renal flare. usCD163 levels were higher in patients with active renal vasculitis compared with patients in remission and those with active extrarenal vasculitis, with median values of 162 ng/mmol (IQR 79-337), 44 (17-104) and 38 (7-76), respectively (P < 0.001). uMCP-1 levels were also higher in patients with active renal vasculitis compared with patients in remission and those with active extrarenal vasculitis, with median values of 10.6 pg/mmol (IQR 4.6-23.5), 4.1 (2.5-8.4) and 4.1 (1.9-6.8), respectively (P < 0.001). The proposed diagnostic cut-points for usCD163 and uMCP-1 were 72.9 ng/mmol and 10.0 pg/mmol, respectively. usCD163 and uMCP-1 levels were marginally correlated (r2 = 0.11, P < 0.001). Combining novel and existing biomarkers using recursive tree partitioning indicated that elevated usCD163 plus either elevated uMCP-1 or new/worse proteinuria improved the positive likelihood ratio (PLR) of active renal vasculitis to 19.2.

CONCLUSION: A combination of usCD163 and uMCP-1 measurements appears to be useful in identifying the diagnosis of subtle renal vasculitis flare.