Procalcitonin (PCT) levels for ruling-out bacterial coinfection in ICU patients with influenza: A CHAID decision-tree analysis

作者：Rodriguez Alejandro H^*; Aviles Jurado Francesc X; Diaz Emili; Schuetz Philipp; Trefler Sandra I; Sole Violan Jordi; Cordero Lourdes; Vidaur Loreto; Estella Angel; Pozo Laderas Juan C; Socias Lorenzo; Vergara Juan C; Zaragoza Rafael; Bonastre Juan; Guerrero Jose E; Suberviola Borja; Cilloniz Catia; Restrepo Marcos I; Martin Loeches Ignacio

来源：Journal of Infection, 2016, 72(2): 143-151.

DOI：10.1016/j.jinf.2015.11.007

• Procalcitonin
• Influenza A(H1N1)pmd
• Community-acquired pneumonia
• Respiratory coinfection
• CHAID analysis
• Prognosis
• Septic shock

Objectives: To define which variables upon ICU admission could be related to the presence of coinfection using CHAID (Chi-squared Automatic Interaction Detection) analysis.
Methods: A secondary analysis from a prospective, multicentre, observational study (2009 -2014) in ICU patients with confirmed A(H1N1)pdm09 infection. We assessed the potential of biomarkers and clinical variables upon admission to the ICU for coinfection diagnosis using CHAID analysis. Performance of cut-off points obtained was determined on the basis of the bi-nominal distributions of the true (+) and true (-) results.
Results: Of the 972 patients included, 196 (20.3%) had coinfection. Procalcitonin (PCT; ng/mL 2.4 vs. 0.5, p < 0.001), but not C-reactive protein (CRP; mg/dL 25 vs. 38.5; p = 0.62) was higher in patients with coinfection. In CHAID analyses, PCT was the most important variable for coinfection. PCT < 0.29 ng/mL showed high sensitivity (Se = 88.2%), low Sp (33.2%) and high negative predictive value (NPV = 91.9%). The absence of shock improved classification capacity. Thus, for PCT < 0.29 ng/mL, the Se was 84%, the Sp 43% and an NPV of 94% with a post-test probability of coinfection of only 6%.
Conclusion: PCT has a high negative predictive value (94%) and lower PCT levels seems to be a good tool for excluding coinfection, particularly for patients without shock.

• 出版日期2016-2