Comparison of Performance of Equations for Estimated Glomerular Filtration Rate in Chinese Patients with Biopsy-Proven Diabetic Nephropathy

Hindawi Disease Markers Volume 2019, Article ID 4354061, 8 pages https://doi.org/10.1155/2019/4354061 Research Article Comparison of Performance of Equations for Estimated Glomerular Filtration Rate in Chinese Patients with Biopsy-Proven Diabetic Nephropathy Yiting Wang,1 Junlin Zhang,1 Geer Teng,2 Yucheng Wu,1 Qianqian Han,1 Hanyu Li,1 Tingli Wang,1 and Fang Liu 1 1 2 Division of Nephrology, West China Hospital of Sichuan University, Chengdu 610041, China The Faculty of Social Development and Western China Development Studies, Sichuan University, China Correspondence should be addressed to Fang Liu; Received 1 July 2019; Accepted 28 August 2019; Published 15 September 2019 Academic Editor: Hubertus Himmerich Copyright © 2019 Yiting Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. The performance of various equations for estimated glomerular filtration rate (eGFR) in patients with diabetes remains controversial. We aimed to evaluate the performance of equations for eGFR in Chinese patients with diabetic nephropathy (DN). Methods. This is a retrospective study included in 308 patients with type 2 diabetes and biopsy-proven DN who were followed up at least one year. eGFR was calculated using chronic kidney disease epidemiology (CKD-EPI) equations based on serum creatinine (eGFRCKD-EPI-Cr), cystatin C (eGFRCKD-EPI-CysC), and joint equations (eGFRCKD-EPI-Cr-CysC), respectively. End-stage kidney disease was defined by initiation of renal replacement therapy. The eGFR concordance between equations was assessed by Bland-Altman plots. Log-rank and multivariable logistic regression were employed to evaluate the performance of equations. Results. Overall, the proportion of patients with eGFR < 60 mL/min/1 73m2 was 53%, 70%, and 61% by the equations of eGFRCKD-EPI-Cr, eGFRCKD-EPI-CysC, and eGFRCKD-EPI-Cr-CysC, respectively. Higher disconcordance was observed between equations when eGFR > 60 mL/min/1 73m2 . Compared with eGFRCKD-EPI-Cr, 39% of patients were reclassified (reclassified group) from CKD 1-2 stages to CKD 3-5 stages by eGFRCKD-EPI-CysC and they presented significantly longer diabetic duration, heavier proteinuria, advanced pathological lesions, and poorer kidney outcomes. Multivariable logistic regression indicated cystatin C was independently associated with advanced glomerular classifications. Conclusion. eGFR equations incorporating cystatin C are superior to eGFR based on creatinine alone for detecting kidney injury in the early stage. The independent association between cystatin C and glomerular classifications might contribute to it. 1. Introduction The past few decades have witnessed a marked increasing prevalence of type 2 diabetes, especially in China, and the global prevalence of microvascular and macrovascular complications associated with diabetes increases dramatically [1, 2]. Diabetic nephropathy (DN) has become the leading cause of end-stage kidney disease (ESKD) worldwide [3, 4]. The utilization of renin-angiotensin-aldosterone system blockers and improvements in glycemic, blood pressure, and lipid control slow the progression of chronic kidney disease (CKD) to a degree [5]. Indeed, glomerular filtration rate (GFR) guides the clinical management of CKD and is an independent predictor of kidney injury, all-cause/cardiovascular mortality, and kidney failure [6]. Therefore, accurate estimation of GFR to identify CKD and predict kidney outcome is highlighted. The Kidney Disease Improving Global Outcomes (KDIGO) 2012 Clinical Practice Guideline for the Evaluation and Management of CKD [7] recommends initial use of 2009 CKD-Epidemiology Collaboration equation based on serum creatinine (eGFRCKD-EPI-Cr) instead of the Modification of Diet in Renal Disease equation. They also suggest use of the 2012 CKD-EPI equations (eGFRCKD-EPI-CysC, eGFRCKD-EPI-Cr-CysC) to confirm kidney function when cystatin C has been measured, particularly for patients 2 with eGFRCr of 45–59 mL/min/1.73 m2 who do not have markers of kidney damage. However, the performance of various equations in CKD cohorts remains controversial due to serum creatinine is influenced by age, muscle mass, sex, and race; cystatin C level is affected by ages, body mass index, diabetes, and inflammation. Patients with DN are recognized as a special community in CKD. Also, the implications and predictive potential of different equations in patients with DN have yet to be elucidated. The objective of the study was to compare the performance for detecting kidney injury of equations of eGFRCKD-EPI-Cr, eGFRCKD-EPI-CysC, and eGFRCKD-EPI-Cr-CysC in patients with DN in a single center in Southwest China. 2. Method 2.1. Study Population. This is a retrospective cohort study. From November 2003 to March 2018, a total of 308 Chinese patients with type 2 diabetes mellitus (T2DM) and biopsy-proven DN in West China Hospital of Sichuan University were recruited and followed up for at least one year by routine clinical visits. Patients with T2DM and proteinuria > 0 5 g/24 h or eGFR decline were indicated to receive kidney biopsy in our hospital. The diagnoses of T2DM and DN were based upon the criteria recommended by the American Diabetes Association (ADA) in 2018 [8] and the Renal Pathology Society in 2010 [9]. The ESKD was defined by initiation of renal replacement therapy (hemodialysis, peritoneal dialysis, or kidney transplantation). Patients who had malignances, nondiabetic renal disease (NDRD), and NDRD+DN were excluded from the study. The protocol of study was approved by the ethics committee of West China Hospital of Sichuan University and conducted based on the principles of the Declaration of Helsinki; written informed consents were obtained at the time of biopsy from all the patients. 2.2. Clinical and Pathological Characteristics. Diabetic history, data including physical examinations (body mass index, blood pressure, and examination of diabetic retinopathy) and laboratory tests (HbA1c, 24-hour protein excretion, serum creatinine, serum cystatin C, serum lipid), were collected at the time of kidney biopsy from the hospital information system. Creatinine was measured using Jaffe’s assay. Serum creatinine value was calibrated to isotope dilution mass spectrometry (IDMS). Serum cystatin C was measured using an automated particle-enhanced immunoturbidimetric method. Blood samples were collected after 12 hours of fasting in all the patients [10]. Pathological lesions were routinely assessed under light and electron microscopy by at least two nephropathologists according to criteria proposed by the Renal Pathology Society in 2010 [9]. 2.3. Statistical Analysis. GFR was estimated using the equations [11] of eGFRCKD-EPI-Cr, eGFRCKD-EPI-CysC, and eGFRCKD-EPI-Cr-CysC, respectively. The CKD stages 1, 2, 3a, 3b, 4, and 5 were categorized by eGFR (...truncated)