Cohort study with prospectively collected data from a cardiac surgery registry.
A major cardiac surgical hospital within the Netherlands, which is also a referral center for Jehovah’s Witnesses.
Patients (23,860) undergoing cardiac surgery between 1997 and 2013.
Comparisons were done in patients with intraoperative nadir Hb<8 g/dL and/or an Hb decrease≥50%. Comparison (A) between Jehovah’s Witnesses (Witnesses) and matched non-Jehovah’s Witnesses (non-Witnesses) transfused with 1 unit of RBC, and comparison (B) between patients given 1 unit of RBC intraoperatively versus matched non-transfused patients.
Postoperative outcomes were myocardial infarction, renal replacement therapy, stroke, and death. With propensity matching, the authors optimized exchangeability of the compared groups. Adverse outcomes increased with a decreasing Hb both among Witnesses and among non-Witnesses. The incidence of postoperative complications did not differ between Witnesses and matched non-Witnesses who received RBC (adjusted odds ratio 1.44, 95% confidence interval 0.63-3.29). Similarly, postoperative complications did not differ between patients who received a red cell transfusion and matched patients who did not (adjusted odds ratio 0.94, confidence interval 0.72-1.23).
Intraoperative anemia is associated with adverse outcomes after cardiac surgery, and a single RBC transfusion does not seem to influence these outcomes.