Risk prediction with procalcitonin and clinical rules in community-acquired pneumonia.

Abstract

STUDY OBJECTIVE:

The Pneumonia Severity Index and CURB-65 predict outcomes in community-acquired pneumonia but have limitations. Procalcitonin, a biomarker of bacterial infection, may provide prognostic information in community-acquired pneumonia. Our objective is to describe the pattern of procalcitonin in community-acquired pneumonia and determine whether procalcitonin provides prognostic information beyond the Pneumonia Severity Index and CURB-65.

METHODS:

We conducted a multicenter prospective cohort study in 28 community and teaching emergency departments. Patients presenting with a clinical and radiographic diagnosis of community-acquired pneumonia were enrolled. We stratified procalcitonin levels a priori into 4 tiers: I: less than 0.1; II: greater than 0.1 to less than 0.25; III: greater than 0.25 to less than 0.5; and IV: greater than 0.5 ng/mL. Primary outcome was 30-day mortality.

RESULTS:

One thousand six hundred fifty-one patients formed the study cohort. Procalcitonin levels were broadly spread across tiers: 32.8% (I), 21.6% (II), 10.2% (III), and 35.4% (IV). Used alone, procalcitonin had modest test characteristics: specificity (35%), sensitivity (92%), positive likelihood ratio (1.41), and negative likelihood ratio (0.22). Adding procalcitonin to the Pneumonia Severity Index in all subjects minimally improved performance. Adding procalcitonin to low-risk Pneumonia Severity Index subjects (classes I to III) provided no additional information. However, subjects in procalcitonin tier I had low 30-day mortality, regardless of clinical risk, including those in higher risk classes (1.5% versus 1.6% for those in Pneumonia Severity Index classes I to III versus classes IV/V). Among high-risk Pneumonia Severity Index subjects (classes IV/V), one quarter (126/546) were in procalcitonin tier I, and the negative likelihood ratio of procalcitonin tier I was 0.09. Procalcitonin tier I was also associated with lower burden of other adverse outcomes. Similar results were observed with CURB-65 stratification.

CONCLUSION:

Selective use of procalcitonin as an adjunct to existing rules may offer additional prognostic information in high-risk patients.

• Authors: David T Huang, Lisa A Weissfeld, John A Kellum, Donald M Yealy, Lan Kong, Michael Martino, Derek C Angus, GenIMS Investigators
• Journal: Annals of emergency medicine (Ann Emerg Med) Vol. 52 Issue 1 Pg. 48-58.e2 (Jul 2008) ISSN: 1097-6760 [Electronic] United States
• PMID: 18342993 (Publication Type: Journal Article, Multicenter Study)

Chemical References

• Biomarkers
• CALCA protein, human
• Protein Precursors
• Calcitonin
• Calcitonin Gene-Related Peptide

Topics

• Aged
• Biomarkers (blood)
• Calcitonin (blood)
• Calcitonin Gene-Related Peptide
• Community-Acquired Infections (blood, mortality)
• Female
• Humans
• Likelihood Functions
• Male
• Pneumonia (blood, mortality)
• Prognosis
• Prospective Studies
• Protein Precursors (blood)
• Risk Assessment
• Sensitivity and Specificity
• Severity of Illness Index
• Survival Analysis