Use of the Modification of Diet in Renal Disease Equation for Estimating Glomerular Filtration Rate in the Urologic Literature

Purpose: To evaluate the use of the modification of diet in renal disease (MDRD) equation in the urologic literature and the degree to which it is used appropriately. Methods: Medline was queried searching the title, keywords, or abstract of seven urology journals for the exact phrases "MDRD" or "modification of diet in renal disease." Forty-seven articles published between 2004 and 2013 met the inclusion criteria and were reviewed. Each article was reviewed in its entirety and graded on the appropriateness of its use of MDRD to estimate glomerular filtration rate (GFR). Inappropriate use was defined as using the MDRD equation to make comparisons or conclusions about true renal function with the majority of estimated glomerular filtration rate (eGFR) values >60 mL/min per 1.73 m². Results: Of the 47 articles reviewed, 17 (36%) were Grade 1 (appropriate use of MDRD), 20 (43%) were Grade 2 (inappropriate use of MDRD but not critical to claims of article), and 10 (21%) were Grade 3 (inappropriate use of MDRD). Of the Grade 3 articles, only 40% (4 of 10) acknowledged the limitations of this equation for estimating GFR. Conclusions: The majority of articles using the MDRD equation to estimate GFR did so using values where the estimate is quite unstable (eGFR >60 mL/min per 1.73 m²), thereby limiting the validity of the claims. Urologists should reconsider the use of MDRD for comparing estimates of GFR in patients with normal renal function in published articles.