Restrictive versus liberal transfusion strategy for red blood cell transfusion in critically ill patients and in patients with acute coronary syndrome: a systematic review, meta-analysis and trial sequential analysis.

Introduction: The risks and benefits of transfusing critically ill patients continue to evoke controversy. Specifically, the critically ill patients with active ischemic cardiac disease continue to represent a "gray area" in the literature.

Evidence Acquisition: Meta-analysis of the effects of lower versus higher hemoglobin thresholds on mortality in critically ill patients was carried out using PRISMA methodology. A systematic research was performed in PubMed, Embase, and the Cochrane Library (last update, December 2014).

Inclusion Criteria: Anemic critically ill adult patients admitted to intensive care units and/or anemic patients with acute coronary syndrome in which a restrictive vs. liberal transfusion therapy was compared.

Primary Endpoint: mortality. Included studies were subjected to quantifiable analysis, predefined subgroup analysis, trial sequential analysis and predefined sensitivity analysis.

Evidence Synthesis: Thirty RCT's were initially identified; 6 fulfilled the inclusion criteria, including 2156. There were no differences in mortality between the restrictive and liberal groups (RR: 0.86, 95% CI 0.70-1.05 P=0.14), neither in patients with chronic cardiovascular disease subgroup (RR: 1.13, 95% IC 0.88-1.46 P=0.34). However, there is a trend towards decreased mortality in the subgroup critically ill (RR: 0.86, 95% CI 0.73-1.01 P=0.06); while in the subgroup of patients with acute myocardial infarct seems like it might be a non-significant trend towards increased mortality (RR: 3.85, 95% CI 0.82-18.0 P=0.09).

Conclusions: Restrictive strategy is at least as effective to liberal strategy in critically ill patients. Nevertheless, there is insufficient evidence to recommend a restrictive strategy for patients with acute coronary syndrome.