Creatinine- versus cystatin C-based renal function assessment in the Northern Manhattan Study

BackgroundAccurate glomerular filtration rate estimation informs drug dosing and risk stratification. Body composition heterogeneity influences creatinine production and the precision of creatinine-based estimated glomerular filtration rate (eGFRcr) in the elderly. We compared chronic kidney disease (CKD) categorization using eGFRcr and cystatin C-based estimated GFR (eGFRcys) in an elderly, racially/ethnically diverse cohort to determine their concordance.MethodsThe Northern Manhattan Study (NOMAS) is a predominantly elderly, multi-ethnic cohort with a primary aim to study cardiovascular disease epidemiology. We included participants with concurrently measured creatinine and cystatin C. eGFRcr was calculated using the CKD-EPI 2009 equation. eGFRcys was calculated using the CKD-EPI 2012 equation. Logistic regression was used to estimate odds ratios and 95% confidence intervals of factors associated with reclassification from eGFRcr≥60ml/min/1.73m2 to eGFRcys2.ResultsParticipants (n = 2988, mean age 69±10yrs) were predominantly Hispanic, female, and overweight/obese. eGFRcys was lower than eGFRcr by mean 23mL/min/1.73m2. 51% of participants’ CKD status was discordant, and only 28% maintained the same CKD stage by both measures. Most participants (78%) had eGFRcr≥60mL/min/1.73m2; among these, 64% had eGFRcys2. Among participants with eGFRcr≥60mL/min/1.73m2, eGFRcys-based reclassification was more likely in those with age >65 years, obesity, current smoking, white race, and female sex.ConclusionsIn a large, multiethnic, elderly cohort, we found a highly discrepant prevalence of CKD with eGFRcys versus eGFRcr. Determining the optimal method to estimate GFR in elderly populations needs urgent further study to improve risk stratification and drug dosing.背景：精准估算肾小球滤过率（glomerular filtration rate, GFR）可为药物剂量调整与风险分层提供关键依据。老年人群的体成分异质性会影响肌酐生成，进而降低基于肌酐的估算肾小球滤过率（estimated glomerular filtration rate based on creatinine, eGFRcr）的计算精度。本研究在一项老年、多种族/族裔的队列中，对比了基于肌酐的eGFR（eGFRcr）与基于半胱氨酸蛋白酶抑制剂C的估算肾小球滤过率（estimated glomerular filtration rate based on cystatin C, eGFRcys）对慢性肾脏病（chronic kidney disease, CKD）的分类结果，以明确二者的一致性。 方法：北部曼哈顿研究（Northern Manhattan Study, NOMAS）是一项以老年人群为主体的多民族队列，其核心研究目标为开展心血管疾病流行病学调查。本研究纳入了同时完成肌酐与半胱氨酸蛋白酶抑制剂C检测的参与者。eGFRcr采用慢性肾脏病流行病学合作研究组（Chronic Kidney Disease Epidemiology Collaboration, CKD-EPI）2009公式计算，eGFRcys采用CKD-EPI 2012公式计算。采用logistic回归分析估算与eGFRcr≥60ml/min/1.73m²重新分类为eGFRcys<60ml/min/1.73m²相关因素的比值比（odds ratio, OR）及95%置信区间（confidence interval, CI）。 结果：本研究共纳入2988名参与者，平均年龄为69±10岁，参与者以西班牙裔、女性及超重/肥胖人群为主。eGFRcys较eGFRcr平均低23mL/min/1.73m²。51%的参与者的慢性肾脏病分类结果不一致，仅28%的参与者通过两种检测方法得到的CKD分期完全一致。大多数参与者（78%）的eGFRcr≥60mL/min/1.73m²；其中64%的参与者的eGFRcys<60mL/min/1.73m²。在eGFRcr≥60mL/min/1.73m²的参与者中，年龄>65岁、肥胖、当前吸烟、白人种族及女性群体更易出现基于eGFRcys的分期重新分类。 结论：在这项大型多民族老年队列研究中，我们发现采用eGFRcys与eGFRcr得到的慢性肾脏病患病率存在显著差异。在老年人群中，优化肾小球滤过率估算方法的相关研究亟待开展，以提升风险分层与药物剂量调整的精准性。