Sepsis is common and is associated with significant mortality, morbidity and health-care costs. Unfortunately, its diagnosis is not straightforward because its signs and symptoms are neither specific nor sensitive; in addition, microbiological cultures lack specificity, sensitivity and are plagued by high turn-around times. Because the delay in the institution of antimicrobial therapy may be deleterious, broad-spectrum antibiotics are widely used in ICU-patients, even when they are not needed. Procalcitonin may not be the long sought for bio-marker to establish the diagnosis of sepsis but may help decrease the duration of the administered antibiotic courses once they are started.

Recently, a number of studies have shown the utility of procalcitonin (PCT) measurements in reducing the duration of antibiotic treatment in patients with respiratory tract infections presenting to the primary care setting or the emergency department. However, it remains unclear if a similar strategy can be effectively and safely implemented in the critical care setting. We attempt to address the controversy on this issue, by collecting, analyzing and interpreting the currently available relevant evidence. To this end, a systematic review and meta-analysis of the randomized controlled trials reporting on the outcomes of critically ill septic patients managed with or without a procalcitonin-based algorithm will be performed.

Inclusion Criteria:

• Randomized controlled trials (RCTs) that report on the outcomes of critically ill patients managed with a procalcitonin-guided algorithm versus routine practice.
• Participants of any age with proven or suspected sepsis will be considered. - As routine practice, the investigators will consider the institution and discontinuation of antibiotics by the attending physicians with the aid of clinical signs, symptoms, microbiological data, well established laboratory parameters (i.e., white blood cell count) and widely accepted guidelines but without the knowledge of PCT values. The investigators will set no limitations regarding the time, country or language of publications. The investigators will search for trials conducted in critically ill neonates and children.

Exclusion Criteria:

• The investigators will exclude studies that are not RCTs and studies performed outside the ICU, namely in the primary care setting, the emergency department or the clinic.

We will systematically search PubMed, Scopus and the Cochrane Central Register of Controlled Trials to identify relevant randomized controlled trials by using the following search terms: procalcitonin AND ("critically ill" OR "intensive care" OR "critical care"). The reference lists of the initially retrieved articles will also be reviewed. Abstracts of conference proceedings will not be sought because they commonly present data that differ from the full publications. Finally, the corresponding authors of each one of the included studies will be contacted by e-mail for additional information and clarifications if needed.