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Diagnostic performance of serum cystatin C and complement component 1q in lupus nephritis
Bei Xu1, Ya-Mei Zhang1, Yu-Wei Yang1
1Department of Clinical Laboratory, Mianyang Central Hospital, Southwest Medical University, No.12 Changjiaxiang, Jingzhong Street, Mianyang, 621000, Sichuan, China.
Insights
New biomarkers cystatin C (CysC) and complement component 1q (C1q) show promise for diagnosing lupus nephritis (LN). CysC and C1q offer superior diagnostic performance compared to traditional markers, with combined use providing rapid discrimination.
Area of Science:
- Nephrology
- Immunology
- Clinical Diagnostics
Background:
- Accurate, non-invasive biomarkers for lupus nephritis (LN) diagnosis are scarce.
- This study investigated cystatin C (CysC) and complement component 1q (C1q) as potential LN diagnostic markers.
Purpose of the Study:
- To evaluate the diagnostic performance of CysC and C1q for lupus nephritis (LN).
- To compare these novel biomarkers against conventional markers like urea and creatinine.
Main Methods:
- A case-control study included patients with systemic lupus erythematosus (SLE) with and without LN, and healthy controls.
- Serum levels of CysC, C1q, urea, and creatinine were measured; estimated glomerular filtration rates (eGFR) were calculated.
- Receiver operating characteristic (ROC) curve analysis identified diagnostic efficiencies of individual and combined markers.
Main Results:
- Elevated CysC and decreased C1q were observed in active and inactive LN groups compared to SLE and healthy groups.
- CysC or eGFRCysC demonstrated the highest individual diagnostic performance for active LN (AUC=0.906-0.907), followed by C1q (AUC=0.753).
- Combined CysC and C1q achieved high performance (AUC=0.933), approaching the optimal combination including conventional markers (AUC=0.975).
Conclusions:
- CysC and C1q are superior to urea, creatinine, and eGFRCreat for diagnosing active lupus nephritis (LNA).
- While a comprehensive marker combination yielded the best results, CysC and C1q offer a prioritized, cost-effective option for rapid LNA discrimination.
Background:
The information concerning non-invasive, easily obtainable, and accurate biomarkers for diagnosis of lupus nephritis (LN) is extremely limited. The aim of this study was to evaluate the diagnostic performance of cystatin C (CysC) and complement component 1q (C1q) for LN.
Methods:
A case-control study that included 905 patients with systemic lupus erythematosus (SLE) without LN (group SLE), 334 patients with active lupus nephritis (group LNA), 255 patients with inactive lupus nephritis (group LNI), and 497 healthy individuals (group HC) was performed in Mianyang Central Hospital from March 2017 to December 2018. The serum levels of CysC, C1q, urea (Urea), and creatinine (Creat) were measured, and 2 estimated glomerular filtration rates (eGFRCysC and eGFRCreat) were calculated by equations which were based on serum CysC established by our group and the modification of diet in renal disease (MDRD), respectively. ANOVA analysis or Kruskal-Wallis test was used for comparing the differences among the groups, and receiver operating characteristic (ROC) curve was applied to identify the diagnostic efficiencies of individual or combined multiple indicators.
Results:
Significantly elevated CysC and decreased C1q were observed in the LNA and LNI groups, which was in contrast to their levels in the SLE and HC groups. CysC (AUC = 0.906) or eGFRCysC (AUC = 0.907) assessed the highest diagnostic performance on LNA when detected individually, followed by C1q (AUC = 0.753). Joint utilization of C1q and CysC achieved very good performance (AUC = 0.933) which approximated to the best one observed in the combinations of C1q, Urea, CysC, eGFRCreat, and Creat (AUC = 0.975).
Conclusion:
The separately detected CysC (eGFRCysC) and C1q were superior to the conventional biomarkers Urea, Creat, and eGFRCreat in the diagnosis of LNA. Moreover, although the combined detection of Urea, Creat, C1q, CysC, and eGFRCreat had the greatest diagnostic performance, the joint utilization of CysC and C1q could be prioritized for rapid discrimination of LNA if the economic burden is taken into consideration.
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