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Question clinique
How accurate are biomarkers, including C-reactive protein, procalcitonin, and leukocytosis, in the diagnosis of community-acquired pneumonia in adults with respiratory symptoms?
L’Essentiel
This review found that the best evidence supports C-reactive protein (CRP) as the most useful and accurate biomarker for diagnosing community-acquired pneumonia (CAP) in adults presenting with lower respiratory tract symptoms. Procalcitonin has a good positive likelihood ratio (LR+; see the synopsis), but a minimally useful negative likelihood ratio (LR-). Leukocytosis has only modest accuracy that is minimally, if at all, clinically useful. 1b
Référence
Plan de l'etude: Meta-analysis (other)
Financement: Self-funded or unfunded
Cadre: Various (meta-analysis)
Sommaire
These investigators thoroughly searched PubMed and reference lists of pertinent articles for studies that evaluated the accuracy of readily available biomarkers in adult patients who present with symptoms of acute respiratory infection and those with clinically suspected pneumonia. The authors included only studies with at least one biomarker test and an acceptable reference standard (chest radiography or computed tomography) performed on all participants. They did not exclude any studies based on country, year, or language. Two or more individuals independently reviewed potential studies for inclusion and risk of bias using a standard evaluation tool. Discrepancies were resolved through consensus discussion. The authors ended up with 14 studies with a total of 6599 patients. Half of the studies occurred in the emergency department and half occurred in the primary care setting. Of the 14 studies, 8 were scored at low risk of bias, with the remainder considered at moderate risk of bias. Overall, CRP was the most accurate test (CRP < 10 mg/L; LR- = 0.27 and CRP > 20 mg/L, 50 mg/L, and 100 mg/L; LR+ = 2.08, 3.68, and 5.79, respectively). Procalcitonin had a good LR+ (> 0.25 ug/L and 0.50 ug/L; LR+ = 5.43 and 8.25, respectively), but a minimally useful LR-. Leukocytosis was only modestly, if at all, accurate (> 9.5 - 10.5; LR+ = 3.15). Based on existing clinical decision rules using signs and symptoms, if the probability of CAP is 25% or less, a CRP of less than 20 mg/L decreases the probability of CAP to less than 10%, making imaging unlikely to be clinically useful and thus unnecessary.
Reviewer
David C. Slawson, MD
Professor and Vice Chair of Family Medicine for Education and Scholarship
Atrium Health
Professor of Family Medicine, UNC Chapel Hill
Charlotte, NC