title: Impact of metformin use on the prognostic value of lactate in sepsis.
abstract: OBJECTIVE
  The objective of this study is to determine if metformin use affects the prevalence and prognostic value of hyperlactatemia to predict mortality in septic adult emergency department (ED) patients.
  
  
  METHODS
  This is a single-center retrospective cohort study. Emergency department providers identified study subjects; data were collected from the medical record.
  
  
  METHODS
  Adult ED patients with suspected infection and 2 or more systemic inflammatory response syndrome criteria were included. The outcome was 28-day mortality. The primary risk variable was serum lactate (<2.0, 2.0-3.9, ≥ 4.0 mmol/L) categorized by metformin use; covariates: demographics, Predisposition, Infection, Response, Organ Dysfunction score and metformin use contraindications.
  
  
  METHODS
  The study was conducted at an urban teaching hospital; February 1, 2007 to October 31, 2008.
  
  
  RESULTS
  A total of 1947 ED patients were enrolled; 192 (10%) were taking metformin; 305 (16%) died within 28 days. Metformin users had higher median lactate levels than nonusers (2.2 mmol/L [interquartile range, 1.6-3.2] vs 1.9 mmol/L [interquartile range, 1.3-2.8]) and a higher, although nonsignificant, prevalence of hyperlactatemia (lactate ≥ 4.0 mmol/L) (17% vs 13%) (P = .17). In multivariate analysis (reference group nonmetformin users, lactate <2.0 mmol/L), hyperlactatemia was associated with an increased adjusted 28-day mortality risk among nonmetformin users (odds ratio [OR], 3.18; P < .01) but not among metformin users (OR, 0.54; P = .33). In addition, nonmetformin users had a higher adjusted mortality risk than metformin users (OR, 2.49; P < .01). These differences remained significant when only diabetic patients were analyzed.
  
  
  CONCLUSIONS
  In this study of adult ED patients with suspected sepsis, metformin users had slightly higher median lactate levels and prevalence of hyperlactatemia. However, hyperlactatemia did not predict an increased mortality risk in patients taking metformin.
authors.affiliation: Department of Emergency Medicine, UC Davis School of Medicine, Sacramento, CA 95817, USA. greenje164@gmail.com
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Green
authors.forename: Tony
authors.initials: T
authors.lastname: Berger
authors.forename: Nidhi
authors.initials: N
authors.lastname: Garg
authors.forename: Alison
authors.initials: A
authors.lastname: Suarez
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Hagar
authors.forename: Michael S
authors.initials: MS
authors.lastname: Radeos
authors.forename: Edward A
authors.initials: EA
authors.lastname: Panacek
mesh_terms: D000368:Aged; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007773:Lactates / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008687:Metformin / Q000494:pharmacology*; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D018805:Sepsis / Q000097:blood / Q000175:diagnosis* / Q000401:mortality
chemical_list: D007004:Hypoglycemic Agents; D007773:Lactates; D008687:Metformin