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Indications for red blood cell transfusion in cardiac surgery: a systematic review and meta-analysis
Nishith N Patel1, Vassilios S Avlonitis2, Hayley E Jones3
1National Heart & Lung Institute, Imperial College London, London, UK.
Insights
Randomized trials show restrictive red blood cell transfusion is safe for cardiac surgery, contradicting observational studies. These findings guide best practices for blood management in adult cardiac surgery patients.
Area of Science:
- Cardiology
- Transfusion Medicine
- Critical Care Medicine
Background:
- Effective blood management is crucial for patient outcomes in cardiac surgery.
- Current guidelines advocate for restrictive red blood cell transfusion protocols.
- A systematic review was conducted to evaluate evidence informing transfusion decisions in adult cardiac surgery.
Purpose of the Study:
- To systematically review randomized controlled trials (RCTs) and observational studies on red blood cell transfusion in adult cardiac surgery.
- To assess the impact of liberal versus restrictive transfusion thresholds on patient outcomes.
- To inform evidence-based transfusion guidelines for cardiac surgery.
Main Methods:
- A systematic review and meta-analysis of RCTs and observational studies were performed.
- Searches included major databases (PubMed, Embase, Cochrane Library) and reference lists.
- The primary outcome was 30-day mortality; secondary outcomes included morbidity.
Main Results:
- RCTs in cardiac surgery (3352 patients) did not show a significant difference in mortality between liberal and restrictive transfusion thresholds (OR 0.70, P=0.060).
- Observational studies (232,806 patients) suggested higher mortality (OR 2.72, P<0.0001) and morbidity with red blood cell transfusion versus no transfusion in cardiac surgery.
- Trials in non-cardiac surgery (8361 patients) also found no significant mortality benefit for restrictive transfusion (OR 1.10, P=0.16).
Conclusions:
- Evidence from RCTs in cardiac surgery does not support the increased mortality risk suggested by observational studies for liberal red blood cell transfusion.
- Observational studies and trials in non-cardiac surgery should not be used to guide transfusion decisions in adult cardiac surgery.
- Restrictive transfusion strategies are supported by RCT evidence in cardiac surgery, aligning with current guidelines.
Background:
Good blood management is an important determinant of outcome in cardiac surgery. Guidelines recommend restrictive red blood cell transfusion. Our objective was to systematically review the evidence from randomised controlled trials and observational studies that are used to inform transfusion decisions in adult cardiac surgery.
Methods:
We did a systematic review by searching PubMed, Embase, Cochrane Library, and DARE, from inception to May 1, 2015, databases from specialist societies, and bibliographies of included studies and recent relevant review articles. We included randomised controlled trials that assessed the effect of liberal versus restrictive red blood cell transfusion in patients undergoing cardiac and non-cardiac surgery, and observational studies that assessed the effect of red blood cell transfusion compared with no transfusion on outcomes in adult cardiac patients after surgery. We pooled adjusted odds ratios using fixed-effects and random-effects meta-analyses. The primary outcome was 30-day mortality.
Findings:
We included data from six cardiac surgical randomised controlled trials (3352 patients), 19 non-cardiac surgical trials (8361 patients), and 39 observational studies (232,806 patients). The pooled fixed effects mortality odds ratios comparing liberal versus restrictive transfusion thresholds was 0.70 (95% CI 0.49-1.02; p=0.060) for cardiac surgical trials and 1.10 (95% CI 0.96-1.27; p=0.16) for trials in settings other than cardiac surgery. By contrast, observational cohort studies in cardiac surgery showed that red blood cell transfusion compared with no transfusion was associated with substantially higher mortality (random effects odds ratio 2.72, 95% CI 2.11-3.49; p<0.0001) and other morbidity, although with substantial heterogeneity and small study effects.
Interpretation:
Evidence from randomised controlled trials in cardiac surgery refutes findings from observational studies that liberal thresholds for red blood cell transfusion are associated with a substantially increased risk of mortality and morbidity. Observational studies and trials in non-cardiac surgery should not be used to inform treatment decisions or guidelines for patients having cardiac surgery.
Funding:
None.
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