Results
We identified 476 articles (PubMed 320, Embase 156) meeting the inclusion criteria. Of these, seven duplicates were removed. Reviewing of the bibliographies resulted in 11 additional articles. The full texts of 114 articles were assessed for eligibility. An additional 64 reviews were excluded, bringing the total on 50 included articles with a total sample size of 63,586 patients (Figure (Figure1).1). Of the 50 included studies, 46 studies were observational cohort studies and 4 were RCTs. The observational studies included 15 retrospective and 31 prospective studies. Sample size in these studies varied between 19 and 20,288 patients with a median of 384 (IQR 135–1217) patients. Two studies included a heterogeneous population of intensive care patients, all other studies were restricted to trauma patients. The score of the included studies on the Newcastle-Ottawa scale ranged from 6 to 8 with a median of 7. The score of the Cochrane Collaboration’s tool for assessing the risk of bias ranged from 8 to 9 (Tables (Tables11 and and2;2; Table S1 in Supplementary Material).