Concordance of Estimated Glomerular Filtration Rates Using Cockcroft-Gault, Modification of Diet in Renal Disease, and Chronic Kidney Disease Epidemiology in Renal Transplant Recipients

Kidney Function According to Different Equations in Patients Admitted to a Cardiology Unit and Impact on Outcome

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.

Concordance between modification of diet in renal disease, chronic kidney disease epidemiology collaboration and Cockcroft-Gault equations in patients with chronic kidney disease at St. Paul's hospital millennium medical college, Addis Ababa, Ethiopia

Background

The most commonly used glomerular filtration rate estimating equations for drug dosing are Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. However there is still a concern about whether to use MDRD and CKD-EPI interchangeably with CG for drug dosage adjustment.

Methods

The study was initiated to determine the concordance between MDRD, CKD-EPI and CG equations and associated factors in patients with chronic kidney disease at Saint Paul’s Hospital Millennium Medical College (SPHMMC). This was a cross sectional study which involved patient chart review and physicians self-administered questionnaire. Serum creatinine level ≥ 1.2 mg/dL was used as a cutoff point in pre-selection of patients. The correctness of the drug dose prescribed for the level of renal function were compared to the drug database (Lexi-Comp) available through Up-to-date version 21.2.

Results

Among the total of 422 patients, 249 (59%) were males. Mean age of patients was 46.09 years. The use of MDRD equation for drug dose adjustment by physicians working in the renal clinic of SPHMMC was six out of nine physicians. The Pearson correlation coefficient between the CG with MDRD and CKD-EPI equations was r = 0.94, P < 0.001 and r = 0.95, P < 0.001, respectively. The concordance between the CG with MDRD and CKD-EPI equations for FDA assigned kidney function categories was 73.7%, Kappa = 0.644 and 74.9%, Kappa = 0.659, respectively. Concordance between the CG with MDRD and CKD-EPI equations for the drug dosing recommendation was 89.6%, kappa = 0.782 and 92%, kappa = 0.834, respectively. Age > 70 years was associated with discordance between CG and MDRD equations for drug dosing recommendation whereas serum creatinine 1.2–3.5 mg/dL, weight < 61 Kg and age > 70 years were associated with discordance between the CG with MDRD and CKD-EPI equations for FDA assigned kidney function categories. However, none of the factors associated with discordance between CG and CKD-EPI for drug dosing.

Conclusion

MDRD equation can be used interchangeably with CG equation for drug dosing recommended in all adult patients between the age of 18 and 70 years. CKD-EPI can be used interchangeably with CG in all adult Ethiopian patients with CKD.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0783-3) contains supplementary material, which is available to authorized users.

Potential influence of tubular dysfunction on the difference between estimated and measured glomerular filtration rate after kidney transplantation

PURPOSE

Because no consensus exists regarding the most accurate calculation to estimate glomerular filtration rate (GFR) based on serum creatinine concentrations (sCr) after kidney transplantation, this study sought to assess the potential role of tubular dysfunction on GFR estimates using various equations as well as the effect of pharmacologic blockades on tubular secretion of creatinine on creatinine clearance (ClCr).

METHODS

Iohexol GFR (mGFR) was performed in 17 stable kidney transplant recipients(R) at >24 months post-transplantation. Their mean age was 48.3 ± 11.3 years. All R were treated with a calcineurin inhibitor (CNI). At the time of study we measured sCr, 24 hour-ClCr, cystatin C, 24-hour proteinuria, microalbuminuria, FE Na, alfa1-microglobulinuria (alfa1-MG), and CNI concentrations. To block tubular secretion of Cr, recipients were prescribed cimetidine (2400 mg) 2 days before the sCr measurement. Additionally, to exclude dietary influences on sCr, R did not eat meat for 2 days before testing. GFR was estimated using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Cockroft-Gault (C&G), and Cystatin C (Cyst C) GFR equations. Mean kidney graft function over the previous 6 months was used as the control. Pearson correlation was determined between the differences between mGFR and estimatedGFR: Iohexol minus MDRD, EPI, Cyst C or C&G GFR for paired estimates. The diagnostic accuracy of the eGFRs to detect an mGFR of 60 mL/min/1.73 m(2) was examined by receiver operating characteristic curves.

RESULTS

Mean mGFR was 75.2 ± 35.8 mL/min/1.73 m(2). The sCr increased but the 24-hour ClCr, MDRD, EPI, and C&G decreased after vs before cimetidine. The difference was significant for sCr (F = 12.933; P = .002) and MDRD GFR (F = 15.750; P = .001). mGFR was not significantly higher than all pair values of eGFRs, and not significantly lower than 24-hour ClCr before and after cimetidine. However, in comparison to all eGFRs, ClCr after cimetidine most approached mGFR. A significant positive correlation was observed between alfa1-MG and the difference between mGFR and MDRD (before, r = .543 [P = .045]; after cimetidine, 0.568 [P = .034]), EPI (before, r = 0.516 [P = .050]; after cimetidine, r = 0.562 [P = .036]), and ClCr (r = 0.633; P = .016), C&G (P = .581; P = .029) before cimetidine. Accuracy of eGFRs to detect mGFR of 60 mL/min/1.73 m(2) showed EPI GFR before cimetidine to show diagnostic accuracy for patients with GFR >60 mL/min/1.73 m(2) with a sensitivity of 81.8% and a specificity of 71.4%.

CONCLUSIONS

Because mGFR is unavailable in many transplant centers, determination of ClCr after cimetidine may help to achieve a more accurate diagnosis of CKD among transplant patients.