title: Even mild hyperlactatemia is associated with increased mortality in critically ill patients.
abstract: BACKGROUND
  The clinical significance of elevation of lactate levels within the reference range is not well studied. The objective of this study was to determine the best cutoff threshold for serum lactate within the reference range (0.01 to 2.00 mM) that best discriminated between survivors and nonsurvivors of critical illness and to examine the association between relative hyperlactatemia (lactate above the identified threshold) and mortality.
  
  
  METHODS
  This was a retrospective cohort study of adult patients admitted to the medical-surgical intensive care unit (ICU) of a tertiary care academic center. Youden index was calculated to identify the best lactate cutoff threshold that discriminated between survivors and nonsurvivors. Patients with lactate above the identified threshold were defined as having relative hyperlactatemia. Multivariate logistic regression, adjusting for baseline variables, was performed to determine the relationship between the above two ranges of lactate levels and mortality. In addition, a test of interaction was performed to assess the effect of selected subgroups on the association between relative hyperlactatemia and hospital mortality.
  
  
  RESULTS
  During the study period, 2,157 patients were included in the study with mean lactate of 1.3 ± 0.4 mM, age of 55.1 ± 20.3 years, and acute physiology and chronic health evaluation (APACHE) II score of 22.1 ± 8.2. Vasopressors were required in 42.4%. Lactate of 1.35 mM was found to be the best cutoff threshold for the whole cohort. Relative hyperlactatemia was associated with increased hospital mortality (adjusted odds ratio (aOR), 1.60, 95% confidence interval (CI) 1.29 to 1.98), and ICU mortality (aOR, 1.66; 95% CI, 1.26 to 2.17) compared with a lactate level of 0.01 to 1.35 mM. This association was consistent among all examined subgroups.
  
  
  CONCLUSIONS
  Relative hyperlactatemia (lactate of 1.36 to 2.00 mM) within the first 24 hours of ICU admission is an independent predictor of hospital and ICU mortality in critically ill patients.
authors.forename: Asgar H
authors.initials: AH
authors.lastname: Rishu
authors.forename: Raymond
authors.initials: R
authors.lastname: Khan
authors.forename: Hasan M
authors.initials: HM
authors.lastname: Al-Dorzi
authors.forename: Hani M
authors.initials: HM
authors.lastname: Tamim
authors.forename: Saad
authors.initials: S
authors.lastname: Al-Qahtani
authors.forename: Ghassan
authors.initials: G
authors.lastname: Al-Ghamdi
authors.forename: Yaseen M
authors.initials: YM
authors.lastname: Arabi
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D016638:Critical Illness / Q000401:mortality* / Q000628:therapy; D005260:Female; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D065906:Hyperlactatemia / Q000175:diagnosis* / Q000401:mortality* / Q000628:therapy; D007362:Intensive Care Units / Q000639:trends*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies
references.citation: Crit Care. 2008;12(3):216
references.pmid: 18557996
references.citation: Clin Endocrinol Metab. 1976 Nov;5(3):613-25
references.pmid: 13949
references.citation: J Inflamm (Lond). 2010 Jan 28;7:6
references.pmid: 20181046
references.citation: Am J Surg. 2004 Apr;187(4):482-5
references.pmid: 15041495
references.citation: Crit Care. 2010;14(1):R25
references.pmid: 20181242
references.citation: Intensive Care Med. 2003 Aug;29(8):1300-5
references.pmid: 12904861
references.citation: J Crit Care. 2011 Aug;26(4):435.e9-14
references.pmid: 21126850
references.citation: Crit Care. 2004 Dec;8(6):508-12
references.pmid: 15566624
references.citation: Ann Emerg Med. 2005 May;45(5):524-8
references.pmid: 15855951
references.citation: Crit Care Med. 2003 Mar;31(3):705-10
references.pmid: 12626973
references.citation: Crit Care Med. 2008 Jan;36(1):296-327
references.pmid: 18158437
references.citation: Am J Emerg Med. 1995 Nov;13(6):619-22
references.pmid: 7575797
references.citation: Rev Bras Anestesiol. 2007 Dec;57(6):630-8
references.pmid: 19462139
references.citation: N Engl J Med. 2001 Nov 8;345(19):1368-77
references.pmid: 11794169
references.citation: Crit Care Med. 2009 May;37(5):1670-7
references.pmid: 19325467
references.citation: Injury. 2009 Jan;40(1):104-8
references.pmid: 19117566
references.citation: Intensive Care Med. 2007 Jun;33(6):970-7
references.pmid: 17431582
references.citation: Intensive Care Med. 2007 Nov;33(11):1967-71
references.pmid: 17661014
references.citation: Crit Care Med. 2010 Jan;38(1):337; author reply 337-8
references.pmid: 20023494
references.citation: Emerg Med J. 2009 Feb;26(2):118-9
references.pmid: 19164625
references.citation: Crit Care Med. 2009 Aug;37(8):2369-74
references.pmid: 19531949
references.citation: Crit Care. 2009;13(3):R90
references.pmid: 19523194
references.citation: Emerg Med J. 2009 Apr;26(4):254-8
references.pmid: 19307384
references.citation: Crit Care Med. 1985 Oct;13(10):818-29
references.pmid: 3928249
references.citation: Dis Mon. 1989 Apr;35(4):233-300
references.pmid: 2656163
references.citation: Acad Emerg Med. 2010 Mar;17(3):260-8
references.pmid: 20370758
references.citation: Am J Surg. 1996 Feb;171(2):221-6
references.pmid: 8619454
references.citation: J Trauma. 1999 Nov;47(5):964-9
references.pmid: 10568731
references.citation: Am J Clin Pathol. 2007 Jul;128(1):168-71
references.pmid: 17580286
references.citation: J Trauma. 1993 Sep;35(3):349-55
references.pmid: 8371291
references.citation: Am J Respir Crit Care Med. 2010 Sep 15;182(6):752-61
references.pmid: 20463176