title: Potential Impact of Prescribing Metformin According to eGFR Rather Than Serum Creatinine.
abstract: OBJECTIVE
  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.
  
  
  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 m(2); contraindicated, <30 mL/min/1.73 m(2); and indeterminate, 30-44 mL/min/1.73 m(2)). 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.
  
  
  RESULTS
  Among adults with sCr above conventional cutoffs, MDRD eGFR ≥45 mL/min/1.73 m(2) 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 m(2). 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 30-44 mL/min/1.73 m(2), for whom metformin safety is indeterminate, ranging from 784,700 (CKD-EPIcr) to 1,636,000 (CG).
  
  
  CONCLUSIONS
  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.
authors: Division of Nephrology, University of California, San Francisco, San Francisco, CA Center for Vulnerable Populations, San Francisco General Hospital, San Francisco, CA delphine.tuot@ucsf.edu.
authors: Delphine S
authors: DS
authors: Tuot
authors: Department of Biostatistics, University of California, San Francisco, San Francisco, CA.
authors: Feng
authors: F
authors: Lin
authors: Department of Medicine, University of California, San Francisco, San Francisco, CA.
authors: Michael G
authors: MG
authors: Shlipak
authors: Division of Nephrology, University of California, San Francisco, San Francisco, CA Center for Vulnerable Populations, San Francisco General Hospital, San Francisco, CA.
authors: Vanessa
authors: V
authors: Grubbs
authors: Division of Nephrology, University of California, San Francisco, San Francisco, CA.
authors: Chi-yuan
authors: CY
authors: Hsu
authors: Division of Nephrology and Hypertension, Henry Ford Hospital, Detroit, MI.
authors: Jerry
authors: J
authors: Yee
authors: Division of Nephrology, Department of Medicine, University of Michigan, Ann Arbor, MI.
authors: Vahakn
authors: V
authors: Shahinian
authors: Division of Nephrology, Department of Medicine, University of Michigan, Ann Arbor, MI.
authors: Rajiv
authors: R
authors: Saran
authors: Centers for Disease Control and Prevention, Atlanta, GA.
authors: Sharon
authors: S
authors: Saydah
authors: Centers for Disease Control and Prevention, Atlanta, GA.
authors: Desmond E
authors: DE
authors: Williams
authors: Center for Vulnerable Populations, San Francisco General Hospital, San Francisco, CA Department of Medicine, University of California, San Francisco, San Francisco, CA.
authors: Neil R
authors: NR
authors: Powe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D011307:Drug Prescriptions / Q000592:standards*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D009749:Nutrition Surveys; D017410:Practice Guidelines as Topic; D051436:Renal Insufficiency, Chronic / Q000097:blood; D055815:Young Adult
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin; D003404:Creatinine