Table 1.
Details of studies included in meta-analysis (n = 18)
| Study | Study designation | Inclusion population | Exclusion population | Adjustment for confounding |
|---|---|---|---|---|
| Vincent et al. [2] | Prospective, multiple center, observational study in western Europe | All ICU patients | Not reported | Patients’ admission variables |
| Corwin et al. [3] | Prospective, multiple center, observational cohort study in the United States | Not reported | Admission to a pediatric, cardiothoracic, cardiac, neurologic, or burn ICU; renal failure on dialysis | Propensity to receive a transfusion |
| Robinson et al. [32] | Retrospective, observational study | Not reported | Patients with blunt hepatic, splenic, or both injuries | Shock indices and associated injury severity |
| Croce et al. [31] | Retrospective, observational study | Patients with blunt injury and ISS <25, survival of at least 48 hours, and no blood transfusion within the first 48 hours from admission | Patients who received any transfusion within the first 48 hours from admission, ISS > =25 | We use original numbers to analyze RR, because the author reported a distracting result (OR2.46,95%CI, 3.17 to 11.56) |
| Taylor et al. [19] | Prospective, observational, cohort study | All ICU admissions | Not reported | Unadjusted |
| Netzer et al. [33] | Prospective, cohort study | Patients with ALI/ARDS | Patients were excluded if they had current or prior congestive heart failure, respiratory disease, or conditions that mimicked ALI/ARDS, including vasculitis with diffuse alveolar hemorrhage; were burned 30% of total body area; or were lung or bone marrow recipients. | Age, gender, APACHE III score, and precipitating event |
| Ruttinger et al. [34] | Retrospective, observational cohort study | All consecutive cases admitted immediately or delayed after a surgical procedure | Patients who had not undergone surgery during their present hospital stay and who had been admitted only for medical reasons, and patients with a rapidly fatal clinical course or with minimal disease severity | Admission variables, maximum APACHE II score, maximum number of failing organs, duration of invasive ventilation, duration of catecholamine therapy, and duration of renal replacement therapy |
| Vincent et al. [35] | Prospective, multicenter, observational study | All ICU patients | Not reported | Sex and age, type of admission, main medical history, fluid balance, SAPS II, and severity of organ dysfunction on admission as SOFA score |
| Bochicchio et al. [36] | Prospective | Trauma patients admitted >48 hours to the ICU | Not reported | Age, sex, race, and ISS |
| Bursi et al. [37] | Retrospective observational study | Stable patients after elective major vascular surgery | Patients who had hemorrhagic hypovolemic shock requiring emergency RBC transfusion, severely anemic | Baseline characteristics, surgical risk, bleeding, presence of anemia, and propensity to receive transfusion |
| Engoren et al. [38] | Retrospective study | All ICU patients | Cardiac surgical patients | APACHE II scores and propensity to receive a transfusion |
| Sakr et al. [21] | Retrospective study | All surgical ICU patients | Not reported | Patients’ propensity to receive a transfusion |
| Parsons et al. [39] | A secondary analysis | Patients with new-onset ALI, sepsis and shock | Patients with trauma or multiple transfusion | Age, sex, race, randomization arm and APACHE III score |
| Sheth et al. [40] | Retrospective, observational cohort study | Patients with intracerebral hemorrhage | Patients younger than 18 years of age or with ICH secondary to antecedent head trauma, acute ischemic stroke with hemorrhagic transformation, brain tumor, vascular malformation, venous thrombosis, vasculitis of the central nervous system, hematological malignances, blood dyscrasia, or coagulopathy | Anemia, warfarin use, admission GCS score, hematoma volume, hematoma location, and DNR/CMO status |
| Park et al. [4] | Prospective, multicenter observational study | Patients with severe sepsis or septic shock | Not reported | Propensity to receive a transfusion |
| Brophy et al. [41] | A cross-sectional retrospective study | Anemia and renal dysfunction | Patients with anemia of neoplastic diseases or those receiving chemotherapy | Age, race, sex, ICU LOS, ESA use, transfusion status, mechanical ventilation or CPAP status, vasopressor use, severity of, illness, and presence of, following comorbid conditions, GI bleed, sepsis, and neurologic injury. |
| Silva et al. [42] | Prospective observational cohort study | All ICU admissions | Acute coronary syndrome, ischemic stroke, acute hemorrhage, prior transfusion, pregnant women and Jehovah’s Witnesses | Sex, origin, previous disease, ventilation mode |
| Sekhon et al. [43] | Retrospective cohort study | Severe TBI patients | Nontraumatic etiology, consciousness, concomitant traumatic quadriparesis | Age, admission GCS score, insertion of EVD, mean 7-day hemoglobin |
APACHE, acute physiology and chronic health evaluation; CPAP, continuous positive airway pressure; DNR/CMO, do not resuscitate/comfort measures only; ESA, erythropoiesis-stimulating agents; EVD, external ventricular drain; GCS, Glasgow coma score; GI, gastrointestinal; ICU, intensive care unit; LOS, length of stay; OR, odds ratio; RBC, red blood cells; RR, relative risk; SAPS, simplified acute physiology score; SOFA, sepsis-related organ failure assessment; TBI, traumatic brain injury.