Applying biomarkers to clinical practice: a guide for utilizing procalcitonin assays

Prudent use of antimicrobial therapies is an important component in decreasing bacterial resistance. Procalcitonin (PCT) is a novel biomarker proposed as both a diagnostic and prognostic agent for use in various severe infections. Elevated PCT levels have a high sensitivity and specificity for diagnosing infections. This biomarker has been studied as an aid to identify patients requiring antimicrobial initiation, stratify infections according to severity and guide therapy durations. Two commercially available tests are approved for use in the USA. Other biomarkers have been studied for similar indications, but are subject to elevation from chronic inflammatory conditions and medications. The advantage of PCT over other biomarkers is due to the limited disease states and drug therapies that may interfere with this assay. PCT has been studied extensively for use in patients with severe sepsis and septic shock, as well as in lower respiratory tract infections. Decreased antimicrobial utilization without an increase in patient morbidity and mortality has been illustrated through numerous studies using PCT algorithms. Determining the utility of PCT in practice requires a comprehensive evaluation of the impact this biomarker has on outcomes to the patient and healthcare system, as well as examining convenience and cost factors. PCT can be used to assist clinicians in initiating and guiding antimicrobial therapies for specific patient populations, as an adjunct to other diagnostic tools. Further studies examining long-term outcomes of PCT are needed to determine the effect of this intervention on resistance patterns and overall prescribing trends.