Perioperative blood transfusion and postoperative mortality

Abstract

Context. - The risks of blood transfusion have been studied extensively but the benefits and the hemoglobin concentration at which patients should receive a transfusion have not. Objective. - To determine the effect of perioperative transfusion on 30- and 90-day postoperative mortality. Design. - Retrospective cohort study. Setting. - A total of 20 US hospitals between 1983 and 1993. Participants. - A total of 8787 consecutive hip fracture patients, aged 60 years or older, who underwent surgical repair. Main Outcome Measures. - Primary outcome was 30-day postoperative mortality; secondary outcome was 90-day postoperative mortality. The 'trigger' hemoglobin level was defined as the lowest hemoglobin level prior to the first transfusion during the time period or, for patients in the nontranfused group, as the lowest hemoglobin level during the time period. Results. - Overall 30-day mortality was 4.6% (n=402; 95% confidence interval [CI], 4.1%-5.0%); overall 90-day mortality was 9.0% (n =788; 95% Cl, 8.4%-9.6%). A total of 42% of patients (n=3699) received a postoperative transfusion. Among patients with trigger hemoglobin levels between 80 and 100 g/L (8.0 and 10.0 g/dL), 55.6% received a transfusion, while 90.5% of patients with hemoglobin levels less than 80 g/L (8.0 g/dL) received postoperative transfusions. Postoperative transfusion did not influence 30- or 90-day mortality after adjusting for trigger hemoglobin level, cardiovascular disease, and other risk factors for death: for 30-day mortality, the adjusted odds ratio (OR) was 0.96 (95% Cl, 0.74-1.26); for 90-day mortality, the adjusted hazard ratio was 1.08 (95% Cl, 0.90-1.29). Similarly, 30-day mortality after surgery did not differ between those who received a preoperative transfusion and those who did not (adjusted OR, 1.23; 95% Cl, 0.81-1.89). Conclusions. - Perioperative transfusion in patients with hemoglobin levels 80 g/L (8.0 g/dL) or higher did not appear to influence the risk of 30- or 90-day mortality in this elderly population. At hemoglobin concentrations of less than 80 g/L (8.0 g/dL), 90.5% of patients received a transfusion, precluding further analysis of the association of transfusion and mortality.