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Development of a Novel Renal Activity Index of Lupus Nephritis in Children and Young Adults
Author(s) -
Brunner Hermine I.,
Bennett Michael R.,
Abulaban Khalid,
KleinGitelman Marisa S.,
O'Neil Kathleen M.,
Tucker Lori,
Ardoin Stacy P.,
RousterStevens Kelly A.,
Onel Karen B.,
Singer Nora G.,
Anne Eberhard B.,
Jung Lawrence K.,
Imundo Lisa,
Wright Tracey B.,
Witte David,
Rovin Brad H.,
Ying Jun,
Devarajan Prasad
Publication year - 2016
Publication title -
arthritis care and research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.032
H-Index - 163
eISSN - 2151-4658
pISSN - 2151-464X
DOI - 10.1002/acr.22762
Subject(s) - medicine , lupus nephritis , kidney , renal biopsy , creatinine , gastroenterology , endocrinology , disease
Objective Noninvasive estimation of the degree of inflammation seen on kidney biopsy with lupus nephritis (LN) remains difficult. The objective of this study was to develop a Renal Activity Index for Lupus (RAIL) that, based solely on laboratory measures, accurately reflects histologic LN activity. Methods We assayed traditional LN laboratory tests and 16 urine biomarkers (UBMs) in children (n = 47) at the time of kidney biopsy. Histologic LN activity was measured by the National Institutes of Health activity index (NIH‐AI) and the tubulointerstitial activity index (TIAI). High LN‐activity status (versus moderate/low) was defined as NIH‐AI scores >10 (versus ≤10) or TIAI scores >5 (versus ≤5). RAIL algorithms that predicted LN‐activity status for both NIH‐AI and TIAI were derived by stepwise multivariate logistic regression, considering traditional biomarkers and UBMs as candidate components. The accuracy of the RAIL for discriminating by LN‐activity status was determined. Results The differential excretion of 6 UBMs (neutrophil gelatinase–associated lipocalin, monocyte chemotactic protein 1, ceruloplasmin, adiponectin, hemopexin, and kidney injury molecule 1) standardized by urine creatinine was considered in the RAIL. These UBMs predicted LN‐activity (NIH‐AI) status with >92% accuracy and LN‐activity (TIAI) status with >80% accuracy. RAIL accuracy was minimally influenced by concomitant LN damage. Accuracies between 71% and 85% were achieved without standardization of the UBMs. The strength of these UBMs to reflect LN‐activity status was confirmed by principal component and linear discriminant analyses. Conclusion The RAIL is a robust and highly accurate noninvasive measure of LN activity. The measurement properties of the RAIL, which reflect the degree of inflammatory changes as seen on kidney biopsy, will require independent validation.