Renal function assessment in older adults

Background: The glomerular filtration rate (GFR) is considered the gold standard for assessing renal function. According to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, GFR estimation is often carried out using predictive equations that incorporate serum creatinine levels, along with demographic factors such as age, gender, race, and body size. However, these equations exhibit varying levels of accuracy across different populations, necessitating the evaluation of their performance and clinical relevance in diverse patient groups.Objectives: This study aimed to evaluate the performance of three commonly used GFR estimation equations, the Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, along with their race-modified versions, by comparing them with measured 24-hour creatinine clearance (CrCl) in adult patients with chronic kidney disease (CKD).Methods: A cross-sectional descriptive study was conducted at Jos University Teaching Hospital (JUTH) between November 2019 and July 2020, involving 111 consecutively recruited CKD patients. Data collection included medical history, physical examination, laboratory investigations, calculation of CrCl, estimated glomerular filtration rate (eGFR) using different equations, and albumin-creatinine ratio (ACR). Statistical analysis was performed using SPSS version 20 (IBM Inc., Armonk, New York), with p-values <0.05 considered statistically significant.Results: The mean age of participants was 51.1±15.5 years. Diabetes mellitus was the most common cause of CKD, affecting 38% of the cohort. Among participants, 31% and 22% were classified as having stage 5 and stage 4 CKD, respectively. The median CrCl was 26 (9-56) mL/min. The median eGFR values across the equations were as follows: CG, 26 (11-60) mL/min/1.73m²; MDRD, 26 (11-60) mL/min/1.73m²; MDRD1, 22 (9-50) mL/min/1.73m²; CKD-EPI, 26 (10-62) mL/min/1.73m²; and CKD-EPI1, 22 (9-53) mL/min/1.73m². Strong positive correlations were observed between measured CrCl and the estimated GFR from each equation: CG (r=0.948, p=0.001), MDRD (r=0.940, p=0.001), MDRD1 (r=0.939, p=0.001), CKD-EPI (r=0.943, p=0.001), and CKD-EPI1 (r=0.942, p=0.001). Furthermore, significant correlations were found between the different GFR equations themselves, with the highest correlation observed between MDRD and CKD-EPI (r=0.999, p=0.001). The median ACR was 395.5 (45.3-2887.0) mg/g, and albuminuria was present in 82% of participants. All three GFR equations closely approximated the measured CrCl of 26 mL/min/1.73m². The equations performed optimally in patients with GFR values below 45 mL/min, with the CG equation exhibiting the least bias and the highest precision. Regression analysis revealed a significant association between albuminuria and all GFR equations and a notable association between age and CrCl, CG, and CKD-EPI estimates.Conclusion: The CG, MDRD, and CKD-EPI equations demonstrated comparable accuracy to measured 24-hour CrCl in estimating GFR in Nigerian patients with CKD. These findings support the clinical use of these predictive equations for renal function assessment in CKD, though local validation in diverse populations is recommended for optimal clinical application.

detecting chronic kidney disease (CKD) may have important implications for the management of older and frail people. We aimed at investigating whether clinical setting (nursing home: NH versus hospital: H) affects the agreement between glomerular filtration rate (GFR) values estimated by Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI), Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) equations. observational study. comparison between NH residents and H patients. we used data from 177 NH residents, and 439 H patients. the agreement between estimating equations and the odds of a discrepancy >25% between formulas in relation to setting (NH versus H) were investigated. the agreement between MDRD and CKD-EPI formulas was good either in NH (k = 0.82) or H (k = 0.87) patients, while corresponding figures for CG indicate only a fair agreement with CKD-EPI (k = 0.50 for both populations). Setting (NH versus H) was associated with discordance between MDRD and CKD-EPI (OR = 3.97; 95% CI = 1.75-9.01), but not between CG and EPI (OR = 1.25; 95% CI = 0.87-1.81). in NH residents, MDRD and CKD-EPI formulas yield highly concordant GFR values, but CG behaves differently in up to one-third of patients. Such findings have important implications in dosing drugs cleared by the kidney. Setting should be taken into consideration in studies for validation of GFR equations.

PD30-06 TRANSPARENCHYMAL RENAL SURGERY DECREASES KIDNEY FUNCTION IN PATIENTS WITH STONES LARGER THAN 4 CM AND STONES IN MULTIPLE LOCATIONS

Should Estimated Glomerular Filtration Rate Be Adjusted for Race?

Background: This paper aims to evaluate the concordance between the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula and alternative equations and to assess their predictive power for all-cause mortality in unselected patients discharged alive from a cardiology ward. Methods: We retrospectively included patients admitted to our Cardiology Division independently of their diagnosis. The total population was classified according to Kidney Disease: Improving Global Outcomes (KDIGO) categories, as follows: G1 (estimated glomerular filtration rate (eGFR) ≥90 mL/min/1.73 m2); G2 (eGFR 89–60 mL/min/1.73 m2); G3a (eGFR 59–45 mL/min/1.73 m2); G3b (eGFR 44–30 mL/min/1.73 m2); G4 (eGFR 29–15 mL/min/1.73 m2); G5 (eGFR <15 mL/min/1.73 m2). Cockcroft-Gault (CG), CG adjusted for body surface area (CG-BSA), Modification of Diet in Renal Disease (MDRD), Berlin Initiative Study (BIS-1), and Full Age Spectrum (FAS) equations were also assessed. Results: A total of 806 patients were included. Good agreement was found between the CKD-EPI formula and CG-BSA, MDRD, BIS-1, and FAS equations. In subjects younger than 65 years or aged ≥85 years, CKD-EPI and MDRD showed the highest agreement (Cohen’s kappa (K) 0.881 and 0.588, respectively) while CG showed the lowest. After a median follow-up of 407 days, overall mortality was 8.2%. The risk of death was higher in lower eGFR classes (G3b HR4.35; 95%CI 1.05–17.80; G4 HR7.13; 95%CI 1.63–31.23; G5 HR25.91; 95%CI 6.63–101.21). The discriminant capability of death prediction tested with ROC curves showed the best results for BIS-1 and FAS equations. Conclusion: In our cohort, the concordance between CKD-EPI and other equations decreased with age, with the MDRD formula showing the best agreement in both younger and older patients. Overall, mortality rates increased with the renal function decreasing. In patients aged ≥75 years, the best discriminant capability for death prediction was found for BIS-1 and FAS equations.

Aggressive blood pressure reduction and renin–angiotensin system blockade in chronic kidney disease: time for re-evaluation?

We evaluated the performance of the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Cockcroft-Gault (CG) equations against creatinine clearance (CrCl) to estimate glomerular filtration rate (GFR) in 51 patients with Type 2 diabetes. The CrCl value was obtained from the average of two consecutive 24-h urine samples. Results were adjusted for body surface area using the Dubois formula. Serum creatinine was measured using the kinetic Jaffe method and was calibrated to standardized levels. Bland-Altman analysis and kappa statistic were used to examine agreement between measured and estimated GFR. Estimates of GFR from the CrCl, MDRD, CKD-EPI and CG equations were similar (overall P = 0.298), and MDRD (r = 0.58; 95% CI: 0.36-0.74), CKD-EPI (r = 0.55; 95% CI: 0.33-0.72) and CG (r = 0.61; 95% CI: 0.39-0.75) showed modest correlation with CrCl (all P < 0.001). Bias was -0.3 for MDRD, 1.7 for CKD-EPI and -5.4 for CG. All three equations showed fair-to-moderate agreement with CrCl (kappa: 0.38-0.51). The c-statistic for all three equations ranged between 0.75 and 0.77 with no significant difference (P = 0.639 for c-statistic comparison). The MDRD equation seems to have a modest advantage over CKD-EPI and CG in estimating GFR and detecting impaired renal function in sub-Saharan African patients with Type 2 diabetes. The overall relatively modest correlation with CrCl, however, suggests the need for context-specific estimators of GFR or context adaptation of existing estimators.

BackgroundLenalidomide is an immunomodulatory drug used to treat multiple myeloma that requires renal dosing adjustment based on Cockcroft-Gault (CG). Various equations to estimate kidney function exist and pose a potential issue with lenalidomide dosing.ObjectiveThe objective of this analysis was to evaluate the impact of estimating kidney function in newly diagnosed multiple myeloma patients with CG, Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and their potential impact on lenalidomide dosing.MethodsData from 1121 multiple myeloma patients at the time of diagnosis acquired from the Mayo Clinic were used to calculate creatinine clearance (CrCl) using Cockcroft-Gault with actual body weight (CGABW), ideal body weight (CGIBW), or adjusted body weight (CGAdjBW); MDRD; and CKD-EPI for each subject. Discordances in dosing were then analyzed, and lenalidomide exposure was calculated for each subject to assess impact on pharmacokinetics of lenalidomide for patients who received discordant doses.ResultsOverall, approximately 16% of patients received a discordant dose when using MDRD or CKD-EPI instead of CGABW. The most common dose discordance was the decrease of a full dose of lenalidomide 25 mg when using CGABW down to 10 mg and when using MDRD or CKD-EPI with 53.8% to 55.6% of all discordances in this category. When assessing different body weights, the most common discordance was a decrease from 25 to 10 mg when using CGIBW instead of CGABW; the same trend was observed when using CGAdjBW instead as well. Patients were also at risk of over- or underexposure based on area under the concentration versus time curve (AUC) for discordant dosing.Conclusion and RelevanceA significant proportion of patients are at risk of under- or overdose of lenalidomide if CKD-EPI or MDRD are used instead of CGABW. Physicians should use CGABW when estimating renal function to dose lenalidomide.

In Reply to ‘Estimated GFR for Drug Dosing: A Bedside Formula’, ‘Drug Dose Adjustments in Patients With Renal Impairment’, ‘Use of the MDRD Study Equation for Drug Dosing’, and ‘Estimated GFR vs Creatinine Clearance for Drug Dosing’

Background. In clinical practice, the glomerular filtration rate (GFR) is often estimated by the Modification of Diet in Renal Disease (MDRD) or Cockcroft-Gault (CG) formulae. No data are available, however, on the performance of these formulae in Arab individuals. Methods. Plasma creatinine samples were obtained from 90 consecutive normal Arab kidney donors for the estimation of GFR (eGFR) using the simplified MDRD and CG formulae. The GFR was measured in these donors with chromium labelled EDTA {[51Cr] EDTA). Bias was assessed by calculating the difference between the measured GFR and the calculated GFR using each of the two formulae; precision was calculated using the r value of the regression analysis. Results. The group studied consisted of 90 donors, of whom 64 were males (71%). The mean age was 30.8 years (± 9.8) and mean BMI was 25.7 (± 5.7). The measured GFR (mean 112.4 ± 17.5) correlated better with the calculated GFR by CG formula (mean 107.7 ± 29.7) and showed poor correlation with the GFR estimated by the MDRD (mean 89.2 ± 13.8); bias = 4.8 and 23.3, respectively (p = 0.1 and < 0.0001, respectively). The correlation with CG formula was better in males (bias = 2, p = 0.5) and those under 30 years of age (bias = 1.0, p = 0.9). Based on our data, we calculated a correction factor to the CG formula to improve the correlation with the measured GFR in Arab individuals. By multiplying the CG formula by 1.0446, the bias was reduced from 4.8 (p = 0.1) to 0.0 (p = 0.5) with an increase in precision from 0.2 (p = 0.05) to 0.43 (p = 0.0001). Using CG formula, the frequency for values within 30% of the mean of the measured value was 75%, which improved to 80% using the revised formula. Conclusions. CG formula was found to be the most appropriate for calculation of GFR in Arab individuals. It is possible to reduce the bias and improve precision in Arab individuals with normal renal function by multiplying the result obtained by CG formula by 1.0446.

BackgroundAlthough the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation has been recommended for accurate estimates of glomerular filtration rate (eGFR), there is little information regarding differences in GFR estimates obtained using the Cockcroft-Gault (CG) or Modification of Diet in Renal Disease (MDRD) equations in East Asian cancer patients. We investigated discrepancies in GFR and toxicities in patients treated with cisplatin-based chemotherapy using three equations equations.MethodsA total of 229 patients were retrospectively recruited. We calculated eGFR using the three equations and separated patients into three categories based on GFR < 10 (group A), 10–50 (group B), and > 50 (group C) mL/min/1.73m2. We analyzed chemotherapy toxicities.ResultsThe mean eGFR calculated using the CG was the lowest of the values derived using the three equations. Estimates using the MDRD and CKD-EPI equations resulted in reclassifying 32 (71.1%) and 33 (73.3%) of 45 patients, originally placed in group B using the CG into group C. However, only 1 (7.7%) of 13 patients placed in group B using the MDRD were reclassified into group C using the CKD-EPI. Twenty-eight of 45 patients classified into group B using the CG equation were treated with reduced doses of cisplatin. However, these patients did not show significant differences in toxicities compared with other patients taking full doses of cisplatin.ConclusionThe CG equations underestimated GFR compared to the MDRD and CKD-EPI equations. Therefore, when GFR is estimated using CG equations, East Asian cancer patients may receive insufficient doses of chemotherapeutic agents, including cisplatin.

ObjectivesThe aim of the study was to assess the validity of an easy‐to‐calculate chronic kidney disease (CKD) risk score developed by the Data Collection on Adverse Events of Anti‐HIV Drugs (D:A:D) group in a longitudinal observational study of people living with HIV (PLWH) in the USA.MethodsPLWH (2002–2016) without prior exposure to potentially nephrotoxic antiretroviral agents and with at least three estimated glomerular filtration rate (eGFR) test results were identified in the Observational Pharmaco‐Epidemiology Research and Analysis (OPERA®) cohort. Three samples were drawn independently using the same eligibility criteria but each using a different eGFR equation, specifically the Cockcroft–Gault (C‐G), Modification of Diet in Renal Disease (MDRD) or Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) eGFR estimation method. Full and short D:A:D risk scores were applied. CKD was defined as a confirmed decrease in eGFR to < 60 mL/min/1.73 m2 (stages 3–5). Poisson models estimated the association between CKD incidence and a one‐point increase in the continuous risk score. The incidence rate ratio (IRR), adjusted IRR (aIRR), and Harrell's discrimination statistic were used to assess validity.ResultsThere were 19 444, 22 727 and 22 748 PLWH in the OPERA C‐G, CKD‐EPI and MDRD samples, respectively. The median (minimum–maximum) follow‐up duration was 6.1 (0.3–9.1) years in the D:A:D cohort and ranged from 3.2 to 3.5 (0.2–15.5) years in the OPERA validation samples. The observation time for the majority of PLWH in the D:A:D cohort began prior to 2006, in stark contrast to the OPERA validation samples, where the majority of PLWH were observed after 2011. The CKD incidence ranged from 7.3 per 1000 person‐years [95% confidence interval (CI) 6.8, 7.9 per 1000 person‐years] in OPERA C‐G to 11.0 (95% CI 10.4, 11.6 per 1000 person‐years) in OPERA MDRD. In OPERA samples, IRRs by risk group and adjusted IRRs (full risk score) were similar to those in the D:A:D derivation cohort (adjusted IRR 1.3; 95% CI 1.3, 1.3). Harrell's c‐statistic ranged from 0.87 to 0.92 in the OPERA samples, comparable to that in the derivation cohort (0.92). Results for short scores were similar.ConclusionsThe findings support the validity of the D:A:D risk scoring method for assessing CKD (stages 3–5) probability in an exclusively USA‐based sample regardless of eGFR method.

Comparison of CKD Awareness in a Screening Population Using the Modification of Diet in Renal Disease (MDRD) Study and CKD Epidemiology Collaboration (CKD-EPI) Equations

Renal function is often estimated using one of several glomerular filtration rate (GFR) estimating equations. However, there is no consensus which estimating equation performs best in patients with advanced renal failure. We compared the performance of five different estimated GFR (eGFR) equations [Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease (CKD) Epidemiology collaboration (CKD-EPI) and Mayo Clinic and Lund-Malmö] with measured GFR (plasma iohexol clearance) in 2098 referred CKD patients with mGFR <30 mL/min/1.73 m(2). There were 398 patients with an mGFR ≤ 10 mL/min/1.73 m(2), 1974 with a measured GFR (mGFR) 11-20 mL/min/1.73 m(2) and 749 patients with mGFR 21-30 mL/min/1.73 m(2). Across the entire range, the median bias of eGFR was lowest for the Lund-Malmö equation (0.7 mL/min/1.73 m(2)), followed by the CKD-EPI (1.2 mL/min/1.73 m(2)), the MDRD (1.6 mL/min/1.73 m(2)), Mayo Clinic equation (1.7 mL/min/1.73 m(2)) and Cockcroft-Gault equation (4.6 mL/min/1.73 m(2)). The best accuracy within 30% of mGFR was also for Lund-Malmö (76%), while it was similar for CKD-EPI, MDRD and Mayo (65-67%). The Cockcroft-Gault had the worst accuracy of only ∼54%.The median bias was stable across mGFR categories, while the accuracy within 30% of mGFR became worse with decreasing mGFR. All equations performed best among patients with hereditary kidney diseases and tubulointerstitial disease. Accuracy was generally worse for patients >65 years of age and for those with diabetic nephropathy. In patients with advanced renal failure, the GFR-estimating equations show reasonably good performance on the population level. On the individual patient level, they are inaccurate, especially in elderly patients and those with diabetic nephropathy.

Comparison of four equations for estimation of glomerular filtration rate in predicting cardiovascular events and subclinical vascular disease in patients with type-2 diabetes