Conclusion
The LUMINEX platform allows for the convenient and simultaneous measurement of 4 RAIL biomarkers. RAIL scores considering only these 4 biomarkers may be sufficient to accurately capture LN activity.
Methods
Spot urine samples (n = 341) of 46 patients aged 20 to 73 years with or without LN were used. Samples were assayed both by ELISA and multiplex using LUMINEX. RAIL scores and biomarker quantities were assessed for agreement with intraassay correlation coefficients and compared using Bland-Altman and regression.
Results
Biomarker measurement by LUMINEX was successful for NGAL, KIM-1, MCP-1, and adiponectin, but not for ceruloplasmin and hemopexin. There was good agreement of the RAIL obtained from these 4 biomarkers, irrespective of assay method (intraclass correlation coefficient [ICC] = 0.78, 95% confidence interval [CI] = 0.78-0.82). The RAIL scores from 4 biomarkers further correlated with those when considering all 6 biomarkers (ICC = 0.97, 95% CI = 0.96-0.98).