Diagnostic Accuracy of Procalcitonin for Early Aspiration Pneumonia in Critically Ill Patients with Coma: A Prospective Study
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Early diagnostic orientation for differentiating pneumonia from pneumonitis at the early stage after aspiration would be valuable to avoid unnecessary antibiotic therapy. We assessed the accuracy of procalcitonin (PCT) in diagnosing aspiration pneumonia (AP) in intensive care unit (ICU) patients requiring mechanical ventilation after out-of-hospital coma.
Prospective observational 2-year cohort study in a medical-surgical ICU. PCT, C-reactive protein (CRP) and white blood cell count (WBC) were measured at admission (H0) and 6 h (H), H12, H24, H48, H96, and H120 after inclusion. Lower respiratory tract microbiological investigations performed routinely in patients with aspiration syndrome were the reference standard for diagnosing AP. Performance of PCT, CRP, and WBC up to H48 in diagnosing AP was compared based on the areas under the ROC curves (AUC) and likelihood ratios (LR+ and LR−) computed for the best cutoff values.
Of 103 patients with coma, 45 (44%) had AP. Repeated PCT assays demonstrated a significant increase in patients with AP versus without AP from H0 to H120. Among the three biomarkers, PCT showed the earliest change. ROC-AUC values were poor for all three biomarkers. Best ROC-AUC values for diagnosing AP were for CRP at H24 [0.73 (95%CI 0.61–0.84)] and PCT at H48 [0.73 (95%CI 0.61–0.84)]. LR+ was best for PCT at H24 (3.5) and LR− for CRP and WBC at H24 (0.4 and 0.4, respectively).
Early and repeated assays of PCT, CRP, and WBC demonstrated significant increases in all three biomarkers in patients with versus without AP. All three biomarkers had poor diagnostic performance for ruling out AP. Whereas PCT had the fastest kinetics, PCT assays within 48 h after ICU admission do not help to diagnose AP in ICU patients with coma.
KeywordsPneumonia Critical care Mechanical ventilation Diagnostic techniques Neurological
The study was supported by the Centre Hospitalier de Versailles, Versailles, France. We thank the nurses in our medical-surgical intensive care unit for their contribution to the study, M. Bouery-Veysseyre for logistic help, and A. Wolfe for help in preparing the manuscript.
SL and JPB conceived, designed, and supervised the trial. All the investigators collected the data. SL and BG coordinated the data collection. PM was in charge of the statistical analysis. SL and BG analyzed and interpreted the data. MB and AM performed PCT assays. SL and BG wrote the first draft of the manuscript. All authors approved the final version of the manuscript.
Source of support
The study was supported by the Centre Hospitalier de Versailles, Versailles, France.
Compliance with ethical standards
Conflicts of interest
The authors declare that they have no competing interests.
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