title: Metformin use in kidney transplant recipients in the United States: an observational study.
abstract: OBJECTIVE
  Although metformin is contraindicated in patients with increased serum creatinine levels (≥1.5 mg/dl in men, ≥1.4 mg/dl in women) in the United States, its use has not been systematically examined in kidney transplant recipients. We aimed to determine the frequency of metformin use and its associations among kidney transplant recipients, and to assess allograft and patient survival associated with metformin use.
  
  
  METHODS
  In this retrospective cohort study, we linked Scientific Registry of Transplant Recipients data for all incident kidney transplants 2001-2012 and national pharmacy claims (n = 46,914). We compared recipients having one or more pharmacy claims for a metformin-containing product (n = 4,609) and recipients having one or more claims for a non-metformin glucose-lowering agent (n = 42,305).
  
  
  RESULTS
  On average, metformin claims were filled later after transplant and were associated with higher estimated glomerular filtration rates before the first claim. Median serum creatinine (mg/dl) levels before the first claim were lower in recipients with metformin claims than in those with non-metformin claims (1.3 [interquartile range 1.0-1.7] vs. 1.6 [1.2-2.5], respectively; p < 0.0001). Metformin was associated with lower adjusted hazards for living donor (0.55, 95% confidence interval 0.38-0.80; p = 0.002) and deceased donor (0.55, 0.44-0.70; p < 0.0001) allograft survival at 3 years posttransplant, and with lower mortality.
  
  
  CONCLUSIONS
  Despite metformin being contraindicated in renal dysfunction, many kidney transplant recipients receive it, and it is not associated with worse patient or allograft survival.
authors.affiliation: Department of Pharmacy, Hennepin County Medical Center, University of Minnesota, Minneapolis, Minn., USA.
authors.forename: Jenise
authors.initials: J
authors.lastname: Stephen
authors.forename: Teresa L
authors.initials: TL
authors.lastname: Anderson-Haag
authors.forename: Sally
authors.initials: S
authors.lastname: Gustafson
authors.forename: Jon J
authors.initials: JJ
authors.lastname: Snyder
authors.forename: Bertram L
authors.initials: BL
authors.lastname: Kasiske
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Israni
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D006085:Graft Survival; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007356:Insurance, Pharmaceutical Services / Q000706:statistics & numerical data; D016030:Kidney Transplantation / Q000401:mortality* / Q000706:statistics & numerical data; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin; D003404:Creatinine