Objective: To review the current status of risks of blood transfusion.
Data Sources, Extractions, and Synthesis: English-speaking literature, literature search using key works, human data, and follow-up with key bibliographic citations.
Conclusions: Substantial advances have been achieved in blood safety during the last 20 yrs, particularly for transfusion-transmitted viral infections. Currently, the most serious known risks from blood transfusion are administrative error (leading to ABO-incompatible blood transfusion), transfusion-related acute lung injury, and bacterial contamination in platelet products. Emerging pathogens, such as West Nile virus infection emphasize the need for implementation of proactive strategies, such as pathogen inactivation technologies, as well as reactive strategies, such as nucleic acid testing, to ensure continued advances in blood safety.
The rates of disease transmission from blood transfusion were once measured by simply following transfusion recipients over time (1). Current viral disease transmission rates are too low to measure, so that mathematical models (2, 3) are needed to estimate blood risks. The models are based on the fact that disease transmission is thought to occur primarily in the window period (the time after a blood donor is infectious but before any donor screening tests are positive). These models also disregard the fact that due to underlying disease, patients who receive transfusions have 1-yr and 10-yr mortality rates of about 24% and 52%, respectively, and may not live long enough to develop transfusion-transmitted disease (4). The estimates are measured on relatively small numbers with wide confidence intervals and some uncertainty in transfusion transmission rates (2). Nevertheless, estimated risks of transfusion-transmitted diseases for immunocompetent patients (Table 1) (5) are lower than ever before (6, 7). These risks have declined substantially with implementation of nucleic acid testing (NAT), which has shortened infectious window periods and reduced the current estimated risks of posttransfusion hepatitis C and human immunodeficiency virus (HIV) dramatically.