Literature Summary

Major Literature

2015 - Serum PCT as a Diagnostic Biomarker for Sepsis in Burned Pts (Burns, meta-analysis)
  • Method
    • Looked at studies published up to March 2014
    • Study eligible if:
      • Provided sensitivity/specificity and true/false negative/positive data
      • Needed to be primarily adult population
  • Results/Discussion
    • 9 eligible studies
      • Subject number in studies ranged from 25-175
      • Avg age 30s-50s
      • Avg TBSA 30-60%
      • Cutoff of "positive" PCT ranged from 0.5-3 (our cutoff here is 0.5)
    • Data analysis
      • Pooled sensitivity = 0.74 (fraction of pt with sepsis who had a positive PCT)
      • Pooled specificity = 0.88 (fraction of pt without sepsis who had a negative PCT)
      • Pooled positive likelihood ratio = 5.75 (pt with sepsis is 5.75 times more likely to have a positive PCT than healthy pt)
      • Pooled negative likelihood ratio = 0.33 (same concept as above)
      • Pooled diagnostic odds ratio = 22.6 (value of 1 means test can't differentiate pts with sepsis to pts without sepsis, 22.6 = moderate level of accuracy)
      • Area under the ROC = 0.92 (1 = perfect test to differentiate pts with sepsis to pts without sepsis, 0.92 = excellent test)
    • 1 of the study reported that PCT at the time of admission could serve as a prognostic marker, but not enough studies to perform a meta-analysis
  • Conclusion
    • Authors of this paper gives relative affirmative view of PCT
      • "...one of the most promising sepsis biomarkers in burned pts"
    • Threshold at which PCT is positive remains unclear (this is a big issue!)
      • Evaluating the trend of PCT may be more important than absolute values
Since this meta-analysis, 1 other notable study has been published:
 
2014 - A New Marker of Sepsis Post Burn Injury? (Critical Care Med, prospective observational)
  • Methods
    • Prospective observational study
    • 54 pts with =/>15% TBSA burn, intubated with no previous CV comorbidities
      • Got PCT and BNP samples daily to test accuracy for detecting new onset sepsis
        • Why BNP? BNP have been shown to be elevated in sepsis, likely due to myocardial depression that occurs in 50% of pts with septic shock and decrease in BNP clearance (complex pathophys)
    • If pt met the American Burn Association Criteria for Sepsis (see below, different from our usual SIRS + suspected/documented infection) --> cultures sent
  • Results
    • 23 of 54 pts had confirmed sepsis
    • BNP (cutoff = 1200)
      • Sensitivity 96%
      • Specificity 99%
      • Positive likelihood ratio 166
      • Negative likelihood ratio 40
      • Diagnostic odds ratio 4030
      • No correlation between BNP levels and exceeding Parkland formula
    • PCT (cutoff = 1.4)
      • Sensitivity 20%
      • Specificity 64%
      • Positive likelihood ratio 0.6
      • Negative likelihood ratio 1.2
      • Diagnostic odds ratio 0.5
    • Multivariable model analysis adjusted for severity of burn --> BNP is an independent marker of sepsis
  • Conclusion
    • Routine BNP that results in >1200 helpful in identifying pts with sepsis while PCT is not helpful in pts with no CV comorbidities
 
 
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