Registry studies have associated red blood cell (RBC) transfusion with increased in-hospital mortality in patients with acute coronary syndrome (ACS). The impact on long-term mortality after 1-year follow-up remains unknown. Consecutive patients with ACS (n = 2,009) of a prospective Genetic Predisposition of Coronary Artery Disease cohort were followed for a median of 8.6 years (95% confidence interval [CI] 8.59 to 8.69). After discharge, 1,937 (96%) patients survived for over 30 days. Of those survivors, a subgroup of previously transfusion-naïve patients 85/1,937 (4.4%) who had received at least 1 RBC transfusion during hospitalization were compared with 1,278/1,937 patients (66.0%) who had not received any transfusion either during the hospitalization or the entire follow-up. Unadjusted long-term mortality was significantly higher in the patients transfused with RBC compared with their counterparts not transfused with RBC (58.8% vs 20.3%, p <0.001). The results remained significant for hazard ratio (HR) 1.91, 95% CI 1.39 to 2.63, p <0.001, after multivariate Cox proportional hazards model analysis and were similar after 1-year landmark analysis (HR 1.90, 95% CI 1.34 to 2.70, p <0.001). The higher all-cause mortality was largely explained by cancer mortality (15.3% vs 4.1%, p <0.001) and cardiovascular mortality (34.1% vs 12.1%, p <0.001). After 1:1 propensity score matching (n = 65 vs 65), the association of RBC transfusion with worse survival remained significant (HR 2.70, 95% CI 1.48 to 4.95, p = 0.001). Inverse probability weighted Cox analyses turned out similar results (HR 2.07, 95% CI 1.38 to 3.11, p <0.001). In conclusion, the strong association of need for RBC transfusion with increased mortality continued for patients with ACS even after a 1-year follow-up.
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