Estimating Equations for Glomerular Filtration Rate in the Era of Creatinine Standardization

A Systematic Review

Earley, Amy BS
Miskulin, Dana MD, MS
Lamb, Edmund J. PhD
Levey, Andrew S. MD
Uhlig, Katrin MD, MS

From Tufts Medical Center, Boston, Massachusetts, and Kent and Canterbury Hospital, Canterbury, Kent, United Kingdom.

Grant Support: By KDIGO.

Potential Conflicts of Interest: Ms. Earley and Drs. Miskulin and Uhlig report the following: Grant (money to institution): National Kidney Foundation; Support for travel to meetings for the study or other purposes: National Kidney Foundation. Ms. Earley and Dr. Uhlig further report: Fees for participation in review activities such as data monitoring boards, statistical analysis, end point committees, and the like (money to institution): National Kidney Foundation. Dr. Miskulin further reports: Grant: National Kidney Foundation; Employment: Dialysis Clinic. Dr. Lamb: Support for travel to meetings for the study or other purposes: Kidney Disease: Improving Global Outcomes; Grants/grants pending (money to institution): National Institutes of Health. Dr. Levey: Support for travel to meetings for the study or other purposes (money to institution): National Kidney Foundation; Board membership (money to institution): National Kidney Foundation; Grants/grants pending (money to institution): National Kidney Foundation. Disclosures can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M11-2267.

Requests for Single Reprints: Katrin Uhlig, MD, MS, Tufts Medical Center, 800 Washington Street, Box 391, Boston, MA 02111; e-mail, [email protected].

Current author addresses and author contributions are available at www.annals.org.

This article was published at www.annals.org on 7 February 2012.

Current Author Addresses: Ms. Earley and Drs. Miskulin, Levey, and Uhlig: Tufts Medical Center, 800 Washington Street, Box 391, Boston, MA 02111.

Dr. Lamb: East Kent Hospitals University National Health Service Trust, Kent and Canterbury Hospital, Ethelbert Road, Canterbury, Kent CT1 3NG, United Kingdom.

Author Contributions: Conception and design: A. Earley, E.J. Lamb, A.S. Levey, K. Uhlig.

Analysis and interpretation of the data: A. Earley, D. Miskulin, E.J. Lamb, A.S. Levey, K. Uhlig.

Drafting of the article: A. Earley, D. Miskulin, E.J. Lamb, A.S. Levey, K. Uhlig.

Critical revision of the article for important intellectual content: A. Earley, D. Miskulin, E.J. Lamb, A.S. Levey, K. Uhlig.

Final approval of the article: A. Earley, E.J. Lamb, A.S. Levey, K. Uhlig.

Statistical expertise: K. Uhlig.

Obtaining of funding: K. Uhlig.

Administrative, technical, or logistic support: A. Earley, E.J. Lamb, K. Uhlig.

Collection and assembly of data: A. Earley, D. Miskulin, E.J. Lamb, A.S. Levey, K. Uhlig.

Annals of Internal Medicine 156(11):p 785-795, June 5, 2012.

Background:

Clinical laboratories are increasingly reporting estimated glomerular filtration rate (GFR) by using serum creatinine assays traceable to a standard reference material.

Purpose:

To review the performance of GFR estimating equations to inform the selection of a single equation by laboratories and the interpretation of estimated GFR by clinicians.

Data Sources:

A systematic search of MEDLINE, without language restriction, between 1999 and 21 October 2011.

Study Selection:

Cross-sectional studies in adults that compared the performance of 2 or more creatinine-based GFR estimating equations with a reference GFR measurement. Eligible equations were derived or reexpressed and validated by using creatinine measurements traceable to the standard reference material.

Data Extraction:

Reviewers extracted data on study population characteristics, measured GFR, creatinine assay, and equation performance.

Data Synthesis:

Eligible studies compared the MDRD (Modification of Diet in Renal Disease) Study and CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations or modifications thereof. In 12 studies in North America, Europe, and Australia, the CKD-EPI equation performed better at higher GFRs (approximately >60 mL/min per 1.73 m²) and the MDRD Study equation performed better at lower GFRs. In 5 of 8 studies in Asia and Africa, the equations were modified to improve their performance by adding a coefficient derived in the local population or removing a coefficient.

Limitation:

Methods of GFR measurement and study populations were heterogeneous.

Conclusion:

Neither the CKD-EPI nor the MDRD Study equation is optimal for all populations and GFR ranges. Using a single equation for reporting requires a tradeoff to optimize performance at either higher or lower GFR ranges. A general practice and public health perspective favors the CKD-EPI equation.

Primary Funding Source:

Kidney Disease: Improving Global Outcomes.