Potential Impact of Prescribing Metformin According to eGFR Rather Than Serum Creatinine
Published Date:Aug 25 2015
Source:Diabetes Care. 38(11):2059-2067.
Corporate Authors:for the CDC CKD Surveillance Team
Pubmed Central ID:PMC4613912
Funding:U58 DP003839/DP/NCCDPHP CDC HHS/United States
CC999999/Intramural CDC HHS/United States
UL1TR000004/TR/NCATS NIH HHS/United States
K23-DK-094850/DK/NIDDK NIH HHS/United States
K23 DK094850/DK/NIDDK NIH HHS/United States
UL1 TR000004/TR/NCATS NIH HHS/United States
Many societies recommend using estimated glomerular filtration rate (eGFR) rather than serum creatinine (sCr) to determine metformin eligibility. We examined the potential impact of these recommendations on metformin eligibility among U.S. adults.
RESEARCH DESIGN AND METHODS
Metformin eligibility was assessed among 3,902 adults with diabetes who participated in the 1999–2010 National Health and Nutrition Examination Surveys and reported routine access to health care, using conventional sCr thresholds (eligible if <1.4 mg/dL for women and <1.5 mg/dL for men) and eGFR categories: likely safe, ≥45 mL/min/1.73 m2; contraindicated, <30 mL/min/1.73 m2; and indeterminate, 30–44 mL/min/1.73 m2). Different eGFR equations were used: four-variable MDRD, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine (CKD-EPIcr), and CKD-EPI cystatin C, as well as Cockcroft-Gault (CG) to estimate creatinine clearance (CrCl). Diabetes was defined by self-report or A1C ≥6.5% (48 mmol/mol). We used logistic regression to identify populations for whom metformin was likely safe adjusted for age, race/ethnicity, and sex. Results were weighted to the U.S. adult population.
Among adults with sCr above conventional cutoffs, MDRD eGFR ≥45 mL/min/1.73 m2 was most common among men (adjusted odds ratio [aOR] 33.3 [95%CI 7.4–151.5] vs. women) and non-Hispanic Blacks (aOR vs. whites 14.8 [4.27–51.7]). No individuals with sCr below conventional cutoffs had an MDRD eGFR <30 mL/min/1.73 m2. All estimating equations expanded the population of individuals for whom metformin is likely safe, ranging from 86,900 (CKD-EPIcr) to 834,800 (CG). All equations identified larger populations with eGFR 30–44mL/min/1.73 m2, for whom metformin safety is indeterminate, ranging from 784,700 (CKD-EPIcr) to 1,636,000 (CG).
The use of eGFR or CrCl to determine metformin eligibility instead of sCr can expand the adult population with diabetes for whom metformin is likely safe, particularly among non-Hispanic blacks and men.
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