Procalcitonin as a diagnostic marker for sepsis: a systematic review and meta-analysis

Background Procalcitonin is a promising marker for identification of bacterial infections. We assessed the accuracy and clinical value of procalcitonin for diagnosis of sepsis in critically ill patients. Methods We searched Medline, Embase, ISI Web of Knowledge, the Cochrane Library, Scopus, BioMed Central, and Science Direct, from inception to Feb 21,2012, and reference lists of identified primary studies. We included articles written in English, German, or French that investigated procalcitonin for differentiation of septic patients-those with sepsis, severe sepsis, or septic shock-from those with a systemic inflammatory response syndrome of non-infectious origin. Studies of healthy people, patients without probable infection, and children younger than 28 days were excluded. Two independent investigators extracted patient and study characteristics; discrepancies were resolved by consensus. We calculated individual and pooled sensitivities and specificities. We used I-2 to test heterogeneity and investigated the source of heterogeneity by metaregression. Findings Our search returned 3487 reports, of which 30 fulfilled the inclusion criteria, accounting for 3244 patients. Bivariate analysis yielded a mean sensitivity of 0.77 (95% CI 0.72-0.81) and specificity of 0.79 (95% CI 0.74-0.84). The area under the receiver operating characteristic curve was 0.85 (95% CI 0.81-0.88). The studies had substantial heterogeneity (I-2=96%, 95% CI 94-99). None of the subgroups investigated-population, admission category, assay used, severity of disease, and description and masking of the reference standard-could account for the heterogeneity. Interpretation Procalcitonin is a helpful biomarker for early diagnosis of sepsis in critically ill patients. Nevertheless, the results of the test must be interpreted carefully in the context of medical history, physical examination, and microbiological assessment.