Comparison of the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) Study Equations: Risk Factors for and Complications of CKD and Mortality in the Kidney Early Evaluation Program (KEEP)

doi:10.1053/j.ajkd.2010.11.007

American Journal of Kidney Diseases

Volume 57, Issue 3, Supplement 2, March 2011, Pages S9-S16

https://doi.org/10.1053/j.ajkd.2010.11.007 Get rights and content

Background

The National Kidney Foundation has recommended that the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation replace the Modification of Diet in Renal Disease (MDRD) Study equation. Before implementing this change in the Kidney Early Evaluation Program (KEEP), we compared characteristics of reclassified individuals and mortality risk predictions using the new equation.

Methods

Of 123,704 eligible KEEP participants, 116,321 with data available for this analysis were included. Glomerular filtration rate (GFR) was estimated using the MDRD Study (eGFR_MDRD) and CKD-EPI (eGFR_CKD-EPI) equations with creatinine level calibrated to standardized methods. Participants were characterized by eGFR category: >120, 90-119, 60-89, 45-59, 30-44, and <30 mL/min/1.73 m². Clinical characteristics ascertained included age, race, sex, diabetes, hypertension, coronary artery disease, congestive heart failure, cerebrovascular disease, peripheral vascular disease, and anemia. Mortality was determined over a median of 3.7 years of follow-up.

Results

The prevalence of eGFR_CKD-EPI <60 mL/min/1.73 m² was 14.3% compared with 16.8% using eGFR_MDRD. Using eGFR_CKD-EPI, 20,355 participants (17.5%) were reclassified to higher eGFR categories, and 3,107 (2.7%), to lower categories. Participants reclassified upward were younger and less likely to have chronic conditions, with a lower risk of mortality. A total of 3,601 deaths (3.1%) were reported. Compared with participants classified to eGFR of 45-59 mL/min/1.73 m² using both equations, those with eGFR_CKD-EPI of 60-89 mL/min/1.73 m² had a lower mortality incidence rate (6.4 [95% CI, 5.1-7.7] vs 18.5 [95% CI, 17.1-19.9]). Results were similar for all eGFR categories. Net reclassification improvement was 0.159 (P < 0.001).

Conclusions

The CKD-EPI equation reclassifies people at lower risk of CKD and death into higher eGFR categories, suggesting more accurate categorization. The CKD-EPI equation will be used to report eGFR in KEEP.

Section snippets

Study Participants

We included 123,704 eligible KEEP participants, August 2000 through December 31, 2009, from 48 NKF affiliates and 2,634 screening programs in 50 states and the District of Columbia. We excluded participants with missing CKD data, leaving a study population of 116,321.

GFR Estimation

GFR was estimated using the 4-variable MDRD Study equation⁸ (eGFR_MDRD) and the CKD-EPI equation³ (eGFR_CKD-EPI): $GFR = 141 \times \min {(SCr / κ, 1)}^{α} \times \max {(SCr / κ, 1)}^{- 1.209} \times {0.993}^{Age} \times 1.018 [if female] \times 1.159 [if African American],$ where SCr is serum

Results

The median value for eGFR_CKD-EPI was higher than for eGFR_MDRD (85.5 [interquartile range, 31] vs 79.2 [interquartile range, 43] mL/min/1.73 m²). Participants in lower eGFR categories determined using eGFR_CKD-EPI were more likely to be older, male, and white and have higher blood pressure than participants in higher categories (Table 1). They also were more likely to be anemic and have chronic conditions, such as diabetes, hypertension, coronary artery disease, congestive heart failure, and

Discussion

GFR is used in many clinical settings. In KEEP, it is used to identify people with CKD and assess CKD severity. In this study, we show that compared with the MDRD Study equation, use of the CKD-EPI equation resulted in a lower prevalence of eGFR <60 mL/min/1.73 m² and more participants classified to higher eGFR categories. Participants who were reclassified to higher categories using eGFR_CKD-EPI were less likely to have CKD risk factors or comorbid conditions and were at lower risk of death

Acknowledgements

The authors thank Shane Nygaard, BA, and Nan Booth, MSW, MPH, ELS, of the Chronic Disease Group for manuscript preparation and editing, respectively.

Support: This study was supported by grant K23-DK081017, Kidney Function and Aging, from the National Institute of Diabetes and Digestive and Kidney Diseases. The KEEP is a program of the NKF Inc and is supported by Amgen, Abbott, Siemens, Astellas, Fresenius Medical Care, Genzyme, LifeScan, Nephroceuticals, and Pfizer. Dr Stevens receives grant

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To determine the relationship between estimated glomerular filtration rate (eGFR) and mortality in a retrospective cohort of older adults admitted to an acute care for the elderly (ACE) unit.
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In the univariate analysis, patients with severely decreased eGFR had higher mortality than those with a higher eGFR (P = .046). In the group with severely decreased eGFR, survival was lower in the functionally dependent group (Barthel index [IB] < 60) than in the independent group (IB ≥ 60) (log rank test; P = .001). In the multivariate analysis, there was a significant increase in the risk of death in the elderly with severely decreased eGFR (< 30) compared with slightly decreased eGFR (≥ 60) (hazard ratio [HR], 1.44; 95% confidence interval [CI]; 1.02-2.05, P = .039). There was also a significant increase in the risk of death in the dependent elderly compared to the independent ones [HR 1.72; 95% CI; 1.26-2.34, P = .000], those who had the high morbidity (≥ 4) with low albumin (< 3.2 g/dL) compared with those with low morbidity (0-3) and high albumin (≥ 3.2) [HR 1.77; 95% CI; 1.18-2.65, P = .005], and in those with a high (16-102 mg/dL) C-reactive protein (CRP) compared with those with low CRP (0-15) [HR 1.42; 95% CI; 1.01-2.01, P = .043].
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KEEP 2010Comparison of the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) Study Equations: Risk Factors for and Complications of CKD and Mortality in the Kidney Early Evaluation Program (KEEP)

Background

Methods

Results

Conclusions

Section snippets

Study Participants

GFR Estimation

Results

Discussion

Acknowledgements

Am J Kidney Dis

Am J Kidney Dis

Am J Kidney Dis

Am J Kidney Dis

Am J Kidney Dis

A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equationModification of Diet in Renal Disease Study Group

Ann Intern Med

Evaluation of the Modification of Diet in Renal Disease Study equation in a large diverse population

J Am Soc Nephrol

A new equation to estimate glomerular filtration rate

Ann Intern Med

Current status of reporting eGFR

Using standardized serum creatinine values in the Modification of Diet in Renal Disease Study equation for estimating glomerular filtration rate

Ann Intern Med

KEEP 2010
Comparison of the CKD Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) Study Equations: Risk Factors for and Complications of CKD and Mortality in the Kidney Early Evaluation Program (KEEP)