Renal function and risk of hip and vertebral fractures in older women

BACKGROUND: An increased rate of hip fractures has been reported in patients with end-stage renal disease, but the effect of less severe renal dysfunction on fracture risk is uncertain. METHODS: We conducted a case-cohort study within a cohort of 9704 women 65 years or older to compare baseline renal function (estimated glomerular filtration rate [eGFR] using the Cockcroft-Gault equation) in 149 women who subsequently had hip fractures and 150 women who subsequently had vertebral fractures with eGRF in 396 randomly selected women. RESULTS: In models adjusted for age, weight, and calcaneal bone density, decreasing eGFR was associated with increased risk of hip fracture. Compared with women with an eGFR 60 mL/min per 1.73 m(2) or greater, the hazard ratio (95% confidence interval [CI]) for hip fracture was 1.57 (95% CI, 0.89-2.76) in those with an eGFR 45 to 59 mL/min per 1.73 m(2) and 2.32 (95% CI, 1.15-4.68) in those with an eGFR less than 45 mL/min per 1.73 m(2) (P for trend = .02). In particular, women with a reduced eGFR were at increased risk of trochanteric hip fracture (adjusted hazard ratio, 3.93 [95% CI, 1.37-11.30] in women with an eGFR 45-59 mL/min per 1.73 m(2) and 7.17 [95% CI, 1.93-26.67] in women with an eGFR <45 mL/min per 1.73 m(2); P for trend = .004). Renal function was not independently associated with risk of vertebral fracture (adjusted odds ratio, 1.08 [95% CI, 0.61-1.92] in women with an eGFR 45-59 mL/min per 1.73 m(2) and 1.33 [95% CI, 0.63-2.80] in women with an eGFR <45 mL/min per 1.73 m(2); P for trend = .47). CONCLUSION: Older women with moderate renal dysfunction are at increased risk of hip fracture.     

Glomerular filtration rate estimated by the CKD-EPI formula is a powerful predictor of in-hospital adverse clinical outcomes after an acute coronary syndrome

The prognostic value of admission estimated glomerular filtration rate (eGFR) calculated by the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula for cardiovascular adverse outcomes in acute coronary syndrome (ACS) was explored. Baseline eGFR was classified as no renal dysfunction (>90 mL/min per 1.73 m(2)), borderline (90-60.1 mL/min per 1.73 m(2)), moderate (60-30.1 mL/min per 1.73 m(2)), or severe (≤30 mL/min per 1.73 m(2)) renal dysfunction. Of the 5034 patients, 3415 (67.8%) had eGFR <90. Compared to patients with an eGFR ≥60 mL/min per 1.73 m(2), patients with <60 mL/min per 1.73 m(2) were less likely to be treated with β-blockers, angiotensin-converting enzyme inhibitors, or statins, or to undergo percutaneous coronary interventions. Lower eGFR showed a stepwise association with significantly worse adverse in-hospital outcomes. The adjusted odds ratio of in-hospital death with an eGFR <30 mL/min per 1.73 m(2) was 3.1 (95% confidence interval 1.1-8.4, P = .0324), compared with an eGFR >90 mL/min per 1.73 m(2). Estimated glomerular filtration rate calculated by the new CKD-EPI is an independent predictor of major adverse cardiac outcomes in patients with ACS.     

急性心肌梗死患者肾功能状态及对预后的影响

目的探评价急性ST段抬高型心肌梗死(STEMI)患者入院即刻肾功能状态及对院内预后的影响。方法多中心、前瞻性队列研究。入选自2005年12月至2007年1月,在发病后24小时内至北京市19家医院就诊的STEMI患者718例。入院即刻测定血清肌酐,根据改良的简化MDRD公式计算估计的肾小球滤过率(eGFR)。分为肾功能正常组(eGFR≥90ml/(min·1.73m2)、轻度肾功能不全组(60ml/(min·1.73m2≤eGFR90ml/(min·1.73m2)和中度肾功能不全组(eGFR60ml/(min·1.73m2),比较三组的临床特点和院内死亡和心血管事件发生情况,采用多元Logistic回归分析影响STEMI患者院内死亡和主要心血管事件的危险因素。结果 718例患者中共有280例(39.0%)已经存在不同程度的肾功能不全(eGFR90ml/min),其中61例(8.5%)为中度以上肾功能不全(eGFR60ml/min)。与肾功能正常组相比,轻度肾功能不全组和中度肾功能不全组患者年龄偏大(57±12)岁vs(66±13)岁vs(72±13)岁,P0.01),女性比例多(16.9%vs39.2%vs48.3%,P0.01),既往有高血压病(47.7%vs59.8%vs70.5%,P0.01),心力衰竭(0%vs2.7%vs6.6%,P0.01),脑卒中或一过性脑缺血(TIA)病史(8.9%vs10.6%vs19.3%,P0.05),入院时心功能Killip≥II级(34.7%vs37.0%vs65.5%,P0.01)较多。院内病死率(1.4%vs5.9%vs22.9%,P0.01)和心血管事件(18.0%vs27.4%vs63.9%,P0.01)显著增高。多因素Logistic回归分析显示入院即刻肾功能不全是STEMI患者发生院内死亡和心血管事件的独立危险因素(OR值分别为3.870;95%CI:1.767-8.474,P0.01和1.712;95%CI:1.217-2.408,P0.01)。结论 STEMI患者中肾功能不全发生率较高,院内死亡及心血管事件的发生率随肾功能恶化而增加,肾功能不全是院内死亡和心血管事件的独立危险因素。     

Valuable markers for contrast-induced nephropathy in patients undergoing cardiac catheterization

Background Contrast-induced nephropathy (CIN) frequently complicates cardiac catheterization, so the objectives of present study were to investigate the usefulness of cystatin C before catheterization and establish a cut-off level for CIN, and to examine the changes in cystatin C and several other markers in patients with and without CIN. Methods and Results Prospective study of consecutive 87 patients who underwent elective catheterization: moderate renal disease defined as glomerular filtration rate 30-59 ml . min(-1) .1.73 mm(-2); cystatin C and creatinine (Cr), urinary liver-type fatty acid-binding protein (L-FABP), alpha(1), beta(2) microglobulins, N-acetyl-beta-D-glucosaminidase, and microalbumin were measured immediately before, and 1, 2, and 3 days after catheterization. CIN occurred in 18 patients and receiver-operating characteristic analysis showed a higher area-under-the-curve for cystatin C compared with serum Cr (0.933 vs 0.832 p=0.012). At a cut-off level of >1.2 mg/L, cystatin C before catheterization exhibited 94.7% (95% confidence interval: 0.851-1.015) sensitivity and 84.8% specificity for detecting CIN. Cystatin C levels were higher in CIN patients than in those without CIN, even before catheterization (cystatin C: 1.08+/-0.22 vs 1.36+/-0.28 mg/L, p=0.007). Urinary L-FABP was increased on days 1 and 2 in patients with moderate renal disease. Conclusion Cystatin C was useful for predicting the occurrence of CIN. Urinary L-FABP was the only marker of transient renotubular damage. (Circ J 2008; 72: 1499 - 1505).     

Estimation of renal function by three CKD-EPI equations in Chinese HIV/AIDS patients: A STROBE-compliant article

Assessing renal function accurately is important for human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) patients. Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) recommended three equations to calculate estimated glomerular filtration rate (eGFR). There is evidence that eGFR based on the combination of serum creatinine and cystatin C is the most accurate of the three equations. But there is limited data on the comparison of three CKD-EPI equations in Chinese HIV/AIDS patients. The aim of our study was to compare the three CKD-EPI equations in Chinese HIV/AIDS population and assess renal function.Cross-sectional, single center, prospective study.One hundred seventy two Chinese adult HIV/AIDS patients were enrolled, including 145 (84.3%) males and 27 (15.7%) females. Mean age was 40(±12) years old. Overall mean eGFR based on serum creatinine, cystatin C and the combination of the 2 markers was 112.6(±19.0) mL/min/1.73 m², 92.0(±24.2)mL/min/1.73 m², and 101.7(±21.8)mL/min/1.73 m², respectively (P = .000). The eGFR calculated by serum creatinine alone is higher than eGFR calculated by combination of serum creatinine and cystatin C, and eGFR calculated by cystatin C individual is lower than eGFR calculated by combination of the 2 markers.Of the 3 CKD-EPI equations, the CKD-EPI_scr-cys equation may have the most accuracy in evaluating renal function in Chinese HIV/AIDS patients while the CKD-EPI_scr equation may overestimate renal function and the CKD-EPI_cys equation may underestimate renal function.     

The relationship between glomerular filtration rate and survival in patients treated with an implantable cardioverter defibrillator

OBJECTIVES: We explored the association between renal insufficiency (RI) and mortality among patients treated with an implantable cardioverter defibrillator (ICD). BACKGROUND: Randomized trials have shown improvements in survival among select patients treated with an ICD. Renal insufficiency patients have a high risk of cardiac death; however, it is not clear whether the ICD has a positive effect on survival in this group of patients. METHODS: This was a retrospective review of a single-center experience of 346 patients treated with an ICD. Patients were stratified into 4 groups according to their glomerular filtration rate (eGFR; expressed as mL/min/ -1.73 m(2)) at implantation: group I, > 75.0; group II, - 60.0 to 74.9; group III, - 45.0 to 59.9; and group IV, - < or = 45.0. All-cause mortality was the primary end point, with differences in survival times among the 4 groups of patients expressed in Kaplan-Meier curves. RESULTS: Mean follow-up was 3.5 y (range 0.1 to 12.9 y), during which 67 patients died (19%). Mortality in each eGFR group was: I - 6.8%, II - 13.8%, III - 11.5%, IV - 45.8% (p < 0.001). Survival times (mean, y) were I, 3.74; II, 3.66; III, 3.38, and IV, 2.82. The presence of diabetes was not a factor in the outcomes. CONCLUSIONS: Patients treated with an ICD with an eGFR of < or = 45.0 mL/min/1.73 m(2) have a significantly shorter survival time than those patients with an eGFR > 45.0 mL/min/1.73 m(2). Patients with an eGFR > 45.0 mL/min/1.73 m(2) appear to have equally good outcomes when treated with an ICD. This may have implications for patient selection for ICD therapy.     

Serum urea nitrogen, creatinine, and estimators of renal function: mortality in older patients with cardiovascular disease

BACKGROUND: Renal dysfunction predicts increased mortality in cardiovascular patients, but the best renal estimator for quantifying risks is uncertain. We compared admission serum urea nitrogen (SUN) level, creatinine level, Modification of Diet in Renal Disease (MDRD) rate, and Mayo estimated glomerular filtration rate (eGFR) for predicting mortality. METHODS: In a retrospective cohort of Medicare patients (aged > or = 65 years) hospitalized for myocardial infarction (n = 44,437) and heart failure (n = 56,652), renal estimators were compared for linearity with 1-year mortality risk, magnitude of risk, and relative importance for predicting risk (percentage variance explained) in proportional hazards models. RESULTS: The SUN level, creatinine level, and Mayo eGFR had linear associations with mortality. These measures predicted steadily increased risk in patients who experienced a myocardial infarction with a SUN level greater than 17 mg/dL (> 6.1 mmol/L), a creatinine level greater than 1.0 mg/dL (> 88.4 micromol/L), and a Mayo eGFR of less than 100 mL/min per 1.73 m2; and in patients who experienced heart failure with a SUN level greater than 16 mg/dL (> 5.7 mmol/L), a creatinine level greater than 1.1 mg/dL (> 97.2 micromol/L), and a Mayo eGFR of 90 mL/min per 1.73 m2 or less. In contrast, the MDRD eGFR had a J-shaped association and failed to identify increased risks in 50.0% of patients who experienced a myocardial infarction (with an MDRD eGFR > 55 mL/min per 1.73 m2) and 60.0% of patients who experienced heart failure (with an MDRD eGFR > 44 mL/min per 1.73 m2). The SUN level and Mayo eGFR had the greatest magnitude of risks. In myocardial infarction and heart failure patients, adjusted mortality increased by 3% and 7%, respectively, per 5-U increase in SUN, and by 3% and 9%, respectively, per 10-U decrease in Mayo eGFR (P<.001), based on models including both renal measures. Of all the measures, SUN had the greatest magnitude of relative importance for predicting mortality. CONCLUSIONS: In older cardiovascular patients, SUN- and creatinine-based measures were powerful predictors of postdischarge mortality. Only MDRD eGFR was less adequate in quantifying risks for patients with mild impairment. Novel estimators, such as the Mayo eGFR, may play an important role in outcomes' prognostication for these patients.     

Decreased glomerular filtration rate is a significant and independent risk for in-hospital mortality in Japanese patients with acute myocardial infarction: report from the Hokkaido acute myocardial infarction registry

Renal dysfunction is a significant risk factor in the prognosis of patients with cardiovascular diseases. We sought to determine the relationship between estimated glomerular filtration rate (eGFR) values and in-hospital mortality in Japanese acute myocardial infarction (AMI) patients. A total of 2266 consecutive AMI patients admitted to 22 hospitals in Hokkaido were registered. The eGFR values were determined using the following equation: eGFR=194 × (serum creatinine)(-1.094) × (age)(-0.287) ( × 0.739 if female). Patients were classified into four groups according to their eGFR values: ≥60 (n=1304), 30-59 (n=810), 15-29 (n=87) and <15 ml min(-1) per 1.73 m(2) (n=65). A total of 110 patients (4.9%) died during hospitalization. The in-hospital mortality rate was significantly higher in patients with reduced eGFR values at 2.3, 5.4, 24.1 and 23.1% for eGFR values of ≥60, 30-59, 15-29, and <15 ml min(-1) per 1.73 m(2), respectively. The odds ratios for in-hospital all cause death were 8.26 (95% confidence interval (CI): 2.22-30.77) for eGFR<15 ml min(-1) per 1.73 m(2) and 3.42 (95% CI: 1.01-11.61) for eGFR 15-29 ml min(-1) per 1.73 m(2) compared with eGFR ≥60?ml?min(-1) per 1.73 m(2). Similarly, the odds ratios for in-hospital cardiac death were 8.43 (95% CI: 1.82-39.05) for eGFR<15 ml min(-1) per 1.73 m(2) and 5.47 (95% CI: 1.51-19.80) for eGFR 15-29 ml min(-1) per 1.73 m(2). In conclusion, the eGFR of <30 ml min(-1) per 1.73 m(2) was a significant and independent risk for in-hospital mortality in abroad cohort of Japanese patients with AMI.     

Cystatin C, a novel measure of renal function, is an independent predictor of cardiac events in patients with heart failure

BACKGROUND: Cystatin C, a novel endogenous marker of glomerular filtration rate, has been reported as more sensitive to detect renal insufficiency than creatinine. The purpose of the present study was to examine the clinical significance of serum cystatin C level in patients with mild to moderate heart failure. METHODS AND RESULTS: Serum levels of cystatin C were measured by an enzyme immunoassay in 140 patients with heart failure and 64 control subjects without heart failure. Patients were prospectively followed during a median follow-up period of 480 days, with the end points of cardiac death and progressive heart failure requiring rehospitalization. Serum levels of cystatin C were higher in patients with heart failure than in control subjects (1.14 +/- 0.60 ng/mL versus 0.72 +/- 0.14 ng/mL, P < .001). The Cox multivariate proportional hazard analysis revealed that a change of 1 standard deviation (SD) in cystatin C level was the one of independent predictor for cardiac events (hazard ratio, 1.94; 95% confidence interval, 1.29-6.64; P < .01). The cardiac event rate was markedly higher in patients with elevated cystatin C level (> or =1.0 ng/mL) than in those with normal level (< or =1.0 ng/mL) (38.7% versus 10.3%, P < 0.001). Furthermore in patients with normal creatinine levels (n = 91), the cardiac event rate was similarly higher in patients with elevated cystatin C than in those with normal levels (29.2% versus 7.5%, P = .002). CONCLUSION: Elevation of serum cystatin C, a new marker of renal function, provides promising prognostic information for clinical outcome in patients with mild to moderate heart failure.     

Serum cystatin C advantageous compared with serum creatinine in the detection of mild but not severe diabetic nephropathy

OBJECTIVE: To determine whether serum cystatin C is more accurate than serum creatinine in the detection of diabetic nephropathy, also after adjustment for age. METHODS: Forty-one patients with type 1 and 82 patients with type 2 diabetes were evaluated with serum creatinine, serum cystatin C, and (51)Cr-EDTA clearance (reference method). Cystatin C was measured by a particle-enhanced turbidimetric method and creatinine by an enzymatic method. Statistical estimations were performed both without and with age adjustment created by z-scores for (51)Cr-EDTA clearance, creatinine, and cystatin C. The cut-off levels for glomerular filtration rate (GFR) ((51)Cr-EDTA clearance) were 60 and 80 mL min(-1) 1.73 m(-2), respectively, in absolute values and 80, 90 and 95% CIs, respectively, in age-adjusted values (z-scores). RESULTS: Estimations without age adjustment showed significantly (P = 0.0132) closer correlation for cystatin C (r = 0.817) versus (51)Cr-EDTA clearance as compared with creatinine (r = 0.678). However, when using age-adjusted values, the correlation for cystatin C and creatinine, respectively, versus (51)Cr-EDTA clearance did not differ. When comparing the diagnostic utilities for serum cystatin C versus serum creatinine in manifest renal impairment (GFR < 60 mL min(-1) 1.73 m(-2) or z-scores <-1.28 SD), there were no significant differences between the two markers whether age adjusted or not. However, for diagnosing mild nephropathy (GFR < 80 mL min(-1) 1.73 m(-2) or z-score -0.84 SD), serum cystatin C is significantly more useful. CONCLUSIONS: Serum cystatin C performed better compared with serum creatinine even when measured enzymatically, to detect mild diabetic nephropathy. However, serum creatinine was as efficient as serum cystatin C to detect advanced diabetic nephropathy.     

肾功能不全对急性心肌梗死患者治疗方案及预后的影响

目的观察肾功能不全对急性心肌梗死(AMI)患者治疗方案及预后的影响。方法入选2011年6月~2012年5月因AMI住院治疗患者523例,根据改良的MDRD方程计算估测的肾小球滤过率(eGFR),根据eGFR水平将患者分为肾功能正常及轻度肾功能不全组(A组,eGFR≥60ml/min.1.73m2),中重度肾功能不全组(B组,eGFR60ml/min.1.73m2)。比较两组患者临床特点、治疗方案和预后的差异。结果 A组患者占71.7%(375/523),B组患者占28.3%(148/523)。与A组患者相比,B组患者年龄偏大、女性较多(P0.01),合并高血压、糖尿病、脑卒中及贫血比例较高(P0.05)。B组患者接受抗凝、β受体阻滞剂、他汀类、ACEI/ARB类药物以及PCI治疗的比例显著低于A组患者(P0.01)。B组患者院内死亡率显著高于A组(P0.01)。影响院内死亡的多因素回归分析显示:除年龄、女性、合并高血压、糖尿病、PCI治疗外,eGFR下降与院内死亡率增加独立相关(OR=6.362,95%CI:2.154~16.892,P0.01)。结论急性心肌梗死合并中重度肾功能不全患者住院期间接受急性心肌梗死指南推荐治疗的比例低于肾功能正常及轻度异常组;急性心肌梗死合并中重度肾功能不全患者院内死亡率增高;中重度肾功能不全是急性心肌梗死患者院内死亡的独立危险因素。     

Renal function and cardiovascular mortality in elderly men: the role of inflammatory, procoagulant, and endothelial biomarkers.

AIMS: To assess the extent to which inflammatory, procoagulant, and endothelial biomarkers modify the relationship between diminished renal function and cardiovascular mortality. METHODS AND RESULTS: Prospective study of 4029 men aged 60-79 years followed up for a mean period of 6 years, during which 304 cardiovascular deaths occurred. Predicted estimated glomerular filtration rate (eGFR) was used as a measure of renal function. Reduced eGFR was associated with increased prevalence of established cardiovascular risk factors [cardiovascular disease, diabetes, hypertension, left ventricular (LV) hypertrophy, and dyslipidaemia] and higher levels of inflammatory markers [interleukin 6 (IL-6), C-reactive protein], endothelial markers [von Willebrand factor (vWF) and tissue plasminogen activator], activated coagulation markers (fibrin D-dimer), and blood viscosity. Cardiovascular mortality risk increased with decreasing levels of eGFR, particularly among men with eGFR <60 mL/min per 1.73 m(2) even after adjustment for established risk factors (adjusted RR 1.49, 95% CI 1.10, 2.03; <60 vs. > or =70 mL/min per 1.73 m(2)). The association was attenuated after further adjustment for vWF, D-dimer, and IL-6 (adjusted RR 1.34, 95% CI 0.98-1.82). CONCLUSION: Mild-to-moderate renal insufficiency is associated with significantly increased cardiovascular mortality in elderly men, which is partly explained by the increased prevalence of established risk factors, markers of coagulation, endothelium, and inflammation.     

Creatinine‐based estimation of glomerular filtration rate in patients with a Fontan circulation

Background: Patients with a Fontan circulation are at risk of renal dysfunction. We analyzed cross‐sectional data in pediatric and adult Fontan patients in order to assess the accuracy of commonly used serum creatinine‐based methods in estimating glo‐ merular filtration rate (GFR). Methods: A total of 124 Fontan patients (58 children, 66 adults) were enrolled across three study centers. Measurement of GFR (mGFR) using in vivo ^99mTc‐DTPA clear‐ ance was performed. Various serum creatinine‐based equations were used to calcu‐ late estimated GFR (eGFR). Results: Mean mGFR was 108 ± 28 mL/min/1.73 m² in children and 92 ± 20 mL/ min/1.73 m² in adults. Fourteen children (25%) and 28 adults (45%) had an mGFR <90 mL/min/1.73 m² . There was no significant correlation between mGFR and eGFR (Schwartz) in children (r = 0.22, P = .1), which substantially overestimated mGFR (bias 50.8, 95%CI: 41.1‐60.5 mL/min/1.73 m² , P < .0001). The Bedside Schwartz equation also performed poorly in the children (r = 0.08, P = .5; bias 5.9, 95%CI: −2.9‐14.6 mL/ min/1.73 m² , P < .0001). There was a strong correlation between mGFR and both eGFR (CKD‐EPI) and eGFR (MDRD) in adults (r = 0.67, P < .0001 in both cases), how‐ ever, both methods overestimated mGFR (eGFR(CKD‐EPI):bias 23.8, 95%CI: 20‐27.6 mL/min/1.73 m² , P < .0001; eGFR (MDRD):bias 16.1, 95%CI: 11.8‐20.4 mL/ min/1.73 m² , P < .0001). None of the children with an mGFR <90 mL/min/1.73 m² had an eGFR (Schwartz) <90 mL/min/1.73 m² . Sensitivity and specificity of eGFR (CKD‐EPI) and eGFR (MDRD) for mGFR <90 mL/min/1.73 m² in adults were 25% and 92% and 39% and 100%, respectively. Conclusions: This study identifies the unreliability of using creatinine‐based equa‐ tions to estimate GFR in children with a Fontan circulation. The accuracy of formulas incorporating cystatin C should be further investigated and may aid noninvasive sur‐ veillance of renal function in this population.     

高敏C反应蛋白对老年女性急性心肌梗死患者肾功能不全的独立预测作用

目的探讨高敏C反应蛋白(hs-CRP)对于老年女性急性心肌梗死(AMI)患者肾功能不全的预测作用。方法选择天津医科大学第二医院就诊的老年女性AMI患者317例,根据估算的肾小球滤过率(eGFR)水平分为肾功能正常组209例[eGFR≥60 ml/(min·1.73 m^2)],肾功能不全组108例[eGFR<60ml/(min·1.73 m^2)]。采用Spearman相关性分析eGFR与临床生化指标的关系,二元logistic回归分析老年女性AMI患者肾功能不全的危险因素。结果与肾功能正常组比较,肾功能不全组年龄、饮酒、KillipsⅡ级、尿酸、尿素、肌酐、hs-CRP、N末端钠尿肽前体、肌酸激酶水平明显升高,TC、LDL-C和白蛋白/球蛋白比值明显降低(P<0.05,P<0.01)。Spearman相关性分析显示,hs-CRP与eGFR呈负相关(r=-0.317,P=0.000)。单因素logistic回归分析显示,hs-CRP是老年女性AMI患者肾功能不全的重要预测指标(OR=1.010,95%CI:1.005~1.015,P=0.000)。多因素logistic回归分析显示,年龄、hs-CRP和N末端钠尿肽前体是老年女性AMI患者肾功能不全的危险因素(P=0.011,P=0.024,P=0.000)。结论 hs-CRP与老年女性AMI患者肾功能密切相关。     

The accuracy of cystatin C and commonly used creatinine-based methods for detecting moderate and mild chronic kidney disease in diabetes.

BACKGROUND: The accuracy of measuring serum cystatin C levels for detecting various stages of chronic kidney disease (CKD) in diabetes is still unclear. METHODS: In a cross-sectional study of 251 subjects, a reference glomerular filtration rate (GFR) was measured using (99c)Tc-DTPA plasma clearance (iGFR). Multivariate analysis was used to identify independent clinical and biochemical associations with serum cystatin C and iGFR levels. The diagnostic accuracy of cystatin C and commonly used creatinine-based methods of measuring renal function (serum creatinine, the MDRD four-variable and Cockcroft-Gault formulae) for detecting mild and moderate CKD was also compared. RESULTS: In the entire study population the same five variables, age, urinary albumin excretion rates, haemoglobin, history of macrovascular disease and triglyceride levels were independently associated with both cystatin C and iGFR levels. A serum cystatin C level cut-off > 82.1 nmol/l (1.10 mg/l) had the best test characteristics as a screening tool for detecting moderate CKD (< 60 ml/min per 1.73 m(2)) when compared with creatinine-based methods. At the upper threshold for mild CKD (< 90 ml/min per 1.73 m(2)), cystatin C also had greater diagnostic accuracy than creatinine, but had similar diagnostic accuracy when compared with creatinine-based formulae for predicting renal function. CONCLUSIONS: This study suggests that the clinical and biochemical parameters associated with serum cystatin C levels are closely linked to those associated with GFR and highlights the potential usefulness of screening for moderate or mild CKD in subjects with diabetes by simply measuring serum cystatin C levels.     

Low Creatinine Potentially Overestimates Glomerular Filtration Rate in Older Fracture Patients: A Plea for an Extensive Use of Cystatin C?

AimMuscle mass is frequently reduced in older patients experiencing injurious falls and may further reduce during hospitalization for bone fracture. In these patients, renal function may be overestimated, because it is usually calculated using serum creatinine, which is strictly related to muscle mass. We evaluated if creatinine levels change during hospitalization in older patients with fracture. We also assessed the role of cystatin C as a more appropriate marker of renal function, comparing estimated glomerular filtration rate (eGFR) according to different formulas based on creatinine and/or cystatin C levels.MethodsPatients aged 65+ years, consecutively hospitalized for fracture, were enrolled in a prospective cohort study. Creatinine and cystatin C levels were measured at baseline and in the post-operative period; eGFR was calculated using six equations based on creatinine and/or cystatin C.Results425 patients were enrolled (mean age 84 years, mean creatinine 0.97 mg/dL, mean cystatin C 1.53 mg/L). Creatinine levels significantly decreased after surgery (p<0.001), while cystatin C remained stable. According to creatinine-based formulas, eGFR was < 60 mL/min/1.73 m² in 29–30% at baseline and only in 17% participants in the post-operative period. Conversely, according to equations including cystatin C, eGFR was < 60 mL/min/1.73 m² in half to three-quarters of the sample at all assessments.ConclusionsIn older fractured patients, creatinine levels decline during hospital stay and may possibly overestimate renal function, whereas cystatin C remains stable. Whether cystatin C is a more reliable marker of renal function in this specific population should be further investigated.     

Association of chronic kidney disease with atrial fibrillation among adults in the United States: REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

BACKGROUND: Atrial fibrillation (AF) is common among patients with end-stage renal disease, but few data are available on its prevalence among adults with chronic kidney disease (CKD) of lesser severity. methods and results: We evaluated the association of CKD with ECG-detected AF among 26 917 participants in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study, a population-based cohort of African-American and white US adults ≥45 years of age. Estimated glomerular filtration rate (eGFR) was calculated using the abbreviated Modification of Diet in Renal Disease study equation and albuminuria was defined as a urinary albumin to creatinine ratio ≥30 mg/g. Participants were categorized by renal function: no CKD (eGFR ≥60 mL/min/1.73 m(2) without albuminuria, n=21 081), stage 1 to 2 CKD (eGFR ≥60 mL/min/1.73 m(2) with albuminuria n=2938), stage 3 CKD (eGFR 30 to 59 mL/min/1.73 m(2), n=2683) and stage 4 to 5 CKD (eGFR <30 mL/min/1.73 m(2), n=215). The prevalence of AF among participants without CKD, and with stage 1 to 2, stage 3, and stage 4 to 5 CKD was 1.0%, 2.8%, 2.7% and 4.2%, respectively. Compared with participants without CKD, the age-, race-, and sex-adjusted odds ratios for prevalent AF were 2.67 (95% confidence interval, 2.04 to 3.48), 1.68 (95% confidence interval, 1.26 to 2.24) and 3.52 (95% confidence interval, 1.73 to 7.15) among those with stage 1 to 2, stage 3, and stage 4 to 5 CKD. The association between CKD and prevalent AF remained statistically significant after further multivariable adjustment and was consistent across numerous subgroups. CONCLUSIONS: Regardless of severity, CKD is associated with an increased prevalence of AF among US adults.     

Chronic kidney disease and functional limitation in older people: health, aging and body composition study

OBJECTIVES: To assess whether chronic kidney disease (CKD) is independently associated with incident physical-function limitation. DESIGN: Prospective cohort study. SETTING: Two sites: Pittsburgh, Pennsylvania, and Memphis, Tennessee. PARTICIPANTS: Two thousand one hundred thirty-five men and women aged 70 to 79 without functional limitation at baseline from the Health, Aging and Body Composition Study. MEASUREMENTS: Functional limitation was defined as difficulty in walking one-quarter of a mile or climbing 10 steps on two consecutive reports 6 months apart (in the same function). Kidney function was measured using serum cystatin C. Estimated glomerular filtration rate (eGFR), using the Modification of Diet in Renal Disease formula (<60 versus > or =60 mL/min per 1.73 m(2)), was a secondary predictor. Muscle strength, lean body mass according to dual energy x-ray absorptiometry, comorbidity, medication use, and inflammatory markers were evaluated as covariates. RESULTS: Persons in the highest (> or =1.13 mg/L) quartile of cystatin C experienced a significantly higher risk of developing functional limitation than those in the lowest (<0.86 mg/L) quartile (hazard ratio (HR)=1.70, 95% confidence interval (CI)=1.40-2.07). The association between the fourth cystatin C quartile and functional limitation remained after adjustment for demographics, lean body mass, comorbidity, muscle strength, and gait speed (HR=1.41, 95% CI=1.13-1.75), although the association was attenuated after adjustment for markers of inflammation (HR=1.15, 95% CI=0.90-1.46). Similar results were found for eGFR less than 60 mL/min per 1.73 m(2), although the association with functional limitation remained after adjustment for inflammatory markers (HR=1.30, 95% CI=1.08-1.56). CONCLUSION: CKD is associated with the development of functional impairment independent of comorbidity, body composition, and tests of strength and physical performance. The mechanism may be related to a heightened inflammatory state in CKD.