title: Severe sepsis cohorts derived from claims-based strategies appear to be biased toward a more severely ill patient population.
abstract: OBJECTIVE
  The epidemiology of severe sepsis is derived from administrative databases that rely on International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes to select cases. We compared the sensitivity of two code abstraction methods in identifying severe sepsis cases using a severe sepsis registry.
  
  
  METHODS
  Single-center retrospective cohort study.
  
  
  METHODS
  Tertiary care, Academic, University Hospital.
  
  
  METHODS
  One thousand seven hundred thirty-five patients with severe sepsis or septic shock.
  
  
  METHODS
  None.
  
  
  METHODS
  Proportion identified as severe sepsis using two code abstraction methods: 1) the new specific ICD-9 codes for severe sepsis and septic shock, and 2) a validated method requiring two ICD-9 codes for infection and end-organ dysfunction. Multivariable logistic regression was performed to determine sociodemographics and clinical characteristics associated with documentation and coding accuracy.
  
  
  RESULTS
  The strategy combining a code for infection and end-organ dysfunction was more sensitive in identifying cases than the method requiring specific ICD-9 codes for severe sepsis or septic shock (47% vs. 21%). Elevated serum lactate level (p<0.001), ICU admission (p<0.001), presence of shock (p<0.001), bacteremia as the source of sepsis (p=0.02), and increased Acute Physiology and Chronic Health Evaluation II score (p<0.001) were independently associated with being appropriately documented and coded. The 28-day mortality was significantly higher in those who were accurately documented/coded (41%, compared with 14% in those who were not, p<0.001), reflective of a more severe presentation on admission.
  
  
  CONCLUSIONS
  Patients admitted with severe sepsis and septic shock were incompletely documented and under-coded, using either ICD-9 code abstracting method. Documentation of subsequent coding of severe sepsis was more common in more severely ill patients. These findings are important when evaluating current national estimates and when interpreting epidemiologic studies of severe sepsis as cohorts derived from claims-based strategies appear to be biased toward a more severely ill patient population.
authors: School of Medicine, University of Pennsylvania, Pulmonary, Allergy, and Critical Care Division, Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA, USA.
authors: Stacey-Ann
authors: SA
authors: Whittaker
authors: Mark E
authors: ME
authors: Mikkelsen
authors: David F
authors: DF
authors: Gaieski
authors: Sherine
authors: S
authors: Koshy
authors: Craig
authors: C
authors: Kean
authors: Barry D
authors: BD
authors: Fuchs
mesh_terms: D000043:Abstracting and Indexing / Q000379:methods*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003422:Critical Care; D016638:Critical Illness / Q000145:classification* / Q000453:epidemiology*; D005260:Female; D006785:Hospitals, University; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D018805:Sepsis / Q000145:classification* / Q000175:diagnosis / Q000453:epidemiology*; D012720:Severity of Illness Index; D012772:Shock, Septic / Q000145:classification / Q000453:epidemiology
references: Am J Respir Crit Care Med. 2008 Feb 1;177(3):279-84
references: 17975201
references: Crit Care Med. 2001 Jul;29(7):1303-10
references: 11445675
references: Crit Care Med. 2003 Apr;31(4):1250-6
references: 12682500
references: Stat Med. 1985 Jan-Mar;4(1):87-90
references: 3992076
references: JAMA. 2011 Nov 23;306(20):2248-54
references: 22081378
references: Chest. 1992 Jun;101(6):1644-55
references: 1303622
references: Ann Emerg Med. 2006 Nov;48(5):583-90, 590.e1
references: 17052559
references: Chest. 2011 Nov;140(5):1223-1231
references: 21852297
references: Crit Care Med. 2007 Aug;35(8):1928-36
references: 17581480
references: Crit Care Med. 2006 Feb;34(2):300-6
references: 16424706
references: JAMA. 2010 Oct 27;304(16):1787-94
references: 20978258
references: Crit Care Med. 2007 May;35(5):1244-50
references: 17414736
references: N Engl J Med. 2001 Nov 8;345(19):1368-77
references: 11794169
references: Crit Care Med. 2009 May;37(5):1670-7
references: 19325467
references: Chest. 2006 Jun;129(6):1432-40
references: 16778259
references: Crit Care Med. 1985 Oct;13(10):818-29
references: 3928249
references: Crit Care Med. 2012 Mar;40(3):754-61
references: 21963582
references: Natl Vital Stat Rep. 2010 May;58(19):1-19
references: 25075874
references: N Engl J Med. 2003 Apr 17;348(16):1546-54
references: 12700374
references: Crit Care. 2004 Aug;8(4):R180-4
references: 15312216
references: Crit Care Med. 2010 Jun;38(6):1442-9
references: 20400903