Association Between Storage Time of Transfused Red Blood Cells and Infection After Clean-contaminated Surgery: A Retrospective Cohort Study.

OBJECTIVE:To investigate the association between the storage time of transfused red blood cells (RBCs) and risks of infections after clean-contaminated surgery. BACKGROUND:Storage lesions of RBCs can aggravate transfusion-related immunomodulation. Very few randomized controlled trials have investigated the impacts of storage time on postoperative outcomes in noncardiac patients. METHODS:We included adult patients who had undergone clean-contaminated surgery from 2014 to 2018 and received allogeneic RBC transfusion. In transfusion episode-level analysis, the exposure was the storage time of each transfusion episode. In patient-level analysis, the exposures were the mean, weighted mean, maximum storage time, and Scalar Age of Blood Index of RBCs transfused into each patient. The primary outcome was infections that developed after transfusions within postoperative day 30. RESULTS:The 4046 patients were included who received 11604 transfusion episodes. Of these, 1025 (25.3%) patients developed postoperative infections. An increased storage time of transfused RBCs was not associated with increased odds of postoperative infections in either transfusion episode-level analysis [odds ratio (OR), 1.03 per 5 days, 95% CI, 0.95-1.11] or patient-level analysis (mean: OR, 1.02, 95% CI, 0.95-1.10; weighted mean: OR, 1.02, 95% CI, 0.95-1.10; maximum: OR, 1.06, 95% CI, 0.98-1.14; Scalar Age of Blood Index: OR, 0.99, 95% CI, 0.96-1.03), after adjusting 17 confounders. CONCLUSIONS:Prolonged storage time of transfused RBCs was not associated with increased risks of infections after clean-contaminated surgery.