Background

The impact of perioperative red blood cell transfusion on long-term outcomes after cardiovascular surgery remains controversial. This meta-analysis of reconstructed time-to-event data aimed to evaluate the association between red blood cell transfusion and clinical outcomes in adult patients undergoing cardiovascular surgery.

Methods

PubMed, Scopus, Embase, and the Cochrane Library were systematically searched for studies comparing perioperative red blood cell transfusion versus no transfusion in adults undergoing cardiovascular surgery. The primary endpoint was all-cause mortality at short- and long-term follow-up. A pairwise random-effects meta-analysis was done for 30-day mortality and other secondary outcomes, pooling risk ratios (RR) with 95% confidence intervals (CIs). Time-to-event data were reconstructed from published Kaplan–Meier curves to perform landmark analysis and estimate restricted mean survival time (RMST) differences between red blood cell transfused and non-transfused groups. Cox frailty regression analysis was used to obtain hazard ratios (HR). Meta-regression analyses were performed to explore sources of heterogeneity, and the certainty of evidence was assessed using the GRADE framework.

Results

This systematic review and meta-analysis included 15 observational studies (13 retrospective and 2 prospective) comparing the impact of red blood transfusion on cardiovascular outcomes in adult patients after cardiovascular surgery. Red blood cell transfusion was associated with a higher incidence of 30-day mortality (RR = 2.57, 95% CI [1.96, 3.38], I² = 0.0%, p < 0.001), long-term all-cause mortality (HR 1.79 (95% CI [1.75, 1.83]; p < 0.001)*, atrial fibrillation (RR 1.57 95% CI [1.21, 2.04]; p < 0.001), acute kidney injury (RR 4.52 95% CI [2.32, 8.80]; p < 0.001), myocardial infarction (RR 2.32 95% CI [1.60, 3.37]; p < 0.001), pneumonia (RR 5.10 95% CI [3.04, 8.57]; p < 0.001), reoperation for bleeding (RR 12.61 95% CI [7.99, 19.90]; p < 0.001), sepsis (RR 7.49 95% CI [2.64, 21.26]; p < 0.001), and stroke (RR 2.54 95% CI [2.04, 3.16]; p < 0.001).

Conclusions

These findings suggest that perioperative red blood cell transfusion was associated with higher rates of mortality and adverse outcomes; however, these findings should be interpreted cautiously because of residual confounding, baseline differences between groups, and the observational nature of the included studies.