Metformin eligibility up with eGFR versus serum creatinine

(HealthDay)—Use of estimated glomerular filtration rate (eGFR) rather than serum creatinine (sCr) can expand metformin eligibility, according to a study published in the November issue of Diabetes Care.

Delphine S. Tuot, M.D., from the University of California in San Francisco, and colleagues examined the potential impact of recommendations to use eGFR rather than sCr to determine metformin eligibility. Metformin eligibility was examined among 3,902 adults with diabetes from the 1999 to 2010 National Health and Nutrition Examination Surveys using conventional sCr thresholds and eGFR categories. Different eGFR equations were used to estimate creatinine clearance (CrCl), including four-variable Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine (CKD-EPIcr), and CKD-EPI cystatin C, as well as Cockcroft-Gault (CG).

The researchers found that MDRD eGFR ≥45 mL/min/1.73 m² was most common for men and non-Hispanic blacks among adults with sCr above conventional cut-offs (adjusted odds ratios, 33.3 versus women and 14.8 versus whites, respectively). An MDRD eGFR <30 mL/min/1.73 m² was not seen among individuals with sCr below conventional cut-offs. The population of individuals for whom metformin is likely safe was expanded with all estimating equations, ranging from 86,900 (CKD-EPIcr) to 834,800 (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," the authors write.