Session Title: Vasculitis IV: Diagnosis and Assessment of Disease Activity
Session Type: ACR Concurrent Abstract Session
Session Time: 9:00AM-10:30AM
Background/Purpose: Prior work has shown that urinary soluble CD163 (usCD163) displays excellent biomarker characteristics for detection of active renal vasculitis using samples from patients with new diagnoses of ANCA-associated vasculitis (AAV) and highly active renal disease. This study focused on use of usCD163 in detection of the more clinically relevant state of mild renal flare, and to compare the performance of usCD163 directly to another proposed biomarker, urinary monocyte chemoattractant protein 1 (uMCP-1).
Methods: Patients with samples obtained during active AAV (n=88) with evidence of active renal involvement (n=34) or without current renal involvement (n=54) were identified within a serially-sampled longitudinal multi-center cohort. In addition, paired remission samples and samples from those with remission AAV were also identified. Creatinine-normalized usCD163 and uMCP-1 levels were measured simultaneously by ELISA. usCD163 and uMCP-1 levels during a flare of active renal vasculitis were compared to levels during remission or during active non-renal AAV.
Results: Samples were available from 320 study visits including times of active renal vasculitis (n=34), remission (n=278), and active extra-renal vasculitis (n=54). Mean creatinine levels in remission and during renal flare were 1.01 mg/dl (SD 0.47) and 1.43 mg/dl (SD 0.61), respectively. usCD163 levels were higher in patients with active renal vasculitis compared with patients in remission and those with active extra-renal vasculitis, with median values of 5.2 pg/mmol (interquartile range (IQR) 1.5-19.4pg/mmol), 0.8pg/mmol (0.1-2.5pg/mmol) and 0.6pg/mmol (0.1-1.6 pg/mmol), 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 extra-renal vasculitis, with median values of 12.6pg/mmol (IQR 5.1-25.1), 2.4pg/mmol (4.1-8.5) and 3.1pg/mmol (1.2-5.5), respectively (p<0.001, Figure 1). The optimal diagnostic cut-offs for usCD163 and uMCP-1 were 1.2pg/mmol and 10.0pg/mmol, respectively. Using these cut-offs, the specificities of usCD163 and uMCP-1 in identifying renal vasculitis flare were 91% and 80%, respectively. Specificities were the same whether comparison was made to remission or to active non-renal AAV. The corresponding sensitivities with these cut-offs were 68% and 64%. The addition of uMCP-1 to usCD163 did not further increase the specificity. usCD163 and uMCP-1 levels were moderately correlated (r² =0.36, p<0.001), suggesting that additional information may be obtained from sequential modelling that incorporates traditional biomarkers.
Conclusion: In the context of subtle renal vasculitis flare, both usCD163 and uMCP1 levels are tightly associated with active renal disease in AAV. Figure 1. Urinary sCD163 and MCP-1 levels in ANCA-associated vasculitis, stratified by disease activity
To cite this abstract in AMA style:Moran SM, Ryan M, Monach PA, Cuthbertson D, Carette S, Dunne J, Hoffman GS, Khalidi NA, Koening CL, Langford CA, McAlear CA, Moreland LW, Pagnoux C, Seo P, Specks U, Sreih AG, Ytterberg SR, Zgaga L, Merkel PA, Little MA. Utility of Measurements of Urinary Soluble CD163 & MCP-1 in the Identification of Subtle Renal Flares in ANCA-Associated Vasculitis [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/utility-of-measurements-of-urinary-soluble-cd163-mcp-1-in-the-identification-of-subtle-renal-flares-in-anca-associated-vasculitis/. Accessed November 19, 2019.
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