Data synthesis
Primary outcomes were risk factors for TIC- and transfusion-associated MOF. Since most of the studies in this field are observational studies, we performed a quality assessment according to the Newcastle-Ottawa Scale (21). Characteristics of the studies examined included comparability of the study groups, methods used to select study participants and determination of outcome variables. The quality of selection of patients in the included studies was rated as good if they included severely injured trauma patients and the control group was drawn from the same community as the exposed cohort. The assessment of comparability of the studies was based on the design and/or analysis used in the studies. Quality of outcome variables was determined by follow-up period and