An electronic database was created to collect all relevant trial data. The data were extracted independently by 2 inves- tigators (MO and MS) and in case of disagreement 2 superpartes referents (LG and LN) cross-examined doubtful data and the decision was made after consensus meeting. Agreement between authors was calculated in order to investigate the risk of bias (Cohen k 1⁄4 0.88).
Information extracted from the trials involved: first author, country of origin, year of publication, number of patients randomized, type of nutritional support, GLN dosage, route of administration, and period of supplementation, regimen of the control groups, Acute Physiology and Chronic Health Evaluation (APACHE) score, Sequential Organ Failure Assess- ment (SOFA) score and number of patients in shock at study entry, intention-to-treat (ITT) reporting, double, single or no blindness, and the different outcome measures.
The primary purpose of this meta-analysis was to evaluate if GLN supplementation could affect mortality. As primary relevant outcomes we assessed the rate of in-hospital and ICU mortality. As secondary endpoint of the analysis we considered the rate of infectious morbidity, the length of in- hospital stay (IHS) and ICU stay (ICUS). All studies reporting on infection defined it as positive specimen culture.
Study quality was assessed by 2 independent reviewers (SC and LN) according to the Jadad score.