The association between transfusion strategies and healthcare-associated infection was recently assessed in a meta-analysis that included 18 randomized trials with a total 7,593 patients that were assigned to either a restrictive or liberal transfusion strategy. The definition of restrictive and liberal transfusion strategies varied amongst individual studies, but most defined a restrictive strategy as the transfusion of red blood cells once hemoglobin falls below either 7.0 or 8.0 grams per deciliter and a liberal strategy as transfusion once hemoglobin falls below 10 grams per deciliter.
The main outcomes of these studies were serious healthcare-associated infections such as pneumonia, mediastinitis, wound infection, and sepsis. The pooled risk of all serious infections was 11.8% in patients treated under a restrictive strategy and 16.9% in patients treated under a liberal strategy. Risk ratio for the association between transfusion strategies and serious infection was 0.82 (95% CI 0.72-0.95). The number needed to treat with a restrictive strategy to avoid one infection was 38 (Rohde JM, et al. JAMA 2014; 311(13): 1317-1326). In the subset of those studies with the most restrictive hemoglobin strategy of <7.0 g/dL, risk ratio remained at 0.82, but the number needed to treat decreased to 20.
When the analysis was stratified by patient type, researchers found that a restrictive strategy in patients undergoing orthopedic surgery and in patients presenting with sepsis significantly reduced the chance of infection, with risk ratios of 0.70 and 0.51, respectively. There were no significant differences in the incidence of infection by hemoglobin threshold for patients with cardiac disease, the critically ill, those with acute upper gastrointestinal bleeding, or low birth weight infants.
More than 80% of patients in this meta-analysis were transfused with leukocyte reduced red blood cells, which are believed to reduce the risks of transfusion associated immunomodulation.
About one in every 20 inpatients develops a nosocomial infection, with estimated annual direct medical costs to U.S. hospitals ranging between $28 billion and $45 billion. Transfusion is associated with immunomodulation, which may affect infection risk. This meta-analysis suggests that adoption of restrictive transfusion strategies might prevent 26 healthcare-associated infections for every 1000 patients in which red blood cell transfusion is under consideration.