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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