This article is more than 5 years old. Information may no longer be current.

Donor age, sex not associated with survival of patients receiving transfusions

Survival is not influenced by the age and sex of blood donors among patients receiving blood transfusion, and blood allocation does not need to consider these factors, according to research published in JAMA Internal Medicine.

“Following reports from animal model studies suggesting that transfusions from young donors may have rejuvenating effects in older recipients, there have been at least two observational studies investigating whether donor age influences the survival of patients receiving transfusions,” Gustaf Edgren, MD, PhD, from Karolinska Institutet in Stockholm, and colleagues wrote. “The studies used dissimilar statistical methods and reported conflicting results. In the first study, which was based on the Scandinavian Donations and Transfusions (SCANDAT2) database, a matched cohort design was used, and no associations were found between donor age and mortality of patients who received transfusions. The second study, based on Canadian data, used a more complex, time-dependent survival model and conversely reported increased risks of death among recipients of blood from young and female donors.”

To reconcile the opposing findings and determine the association between donor age and sex and survival of patients receiving blood transfusions, Edgren and colleagues performed a retrospective cohort study using nationwide data from SCANDAT2 and similar methods to those used in the Canadian study. The analysis included 968,264 patients (550,257 women; median age at first transfusion, 73 years) from Sweden and Denmark who received at least one red blood cell transfusion of autologous blood or blood from unknown donors between Jan. 1, 2003 and Dec. 31, 2012. The researchers followed patients from the first transfusion to death, emigration or end of follow-up and also restricted follow-up at a maximum of 30 days in some analyses to increase the sensitivity for short-term survival effects.

Results showed a U-shaped association between age of the blood donor and recipient mortality when follow-up was restricted to 30 days. This association indicated a nadir in patients receiving blood from donors in the most common donor age group (40-49 years), as well as significant and escalating HRs among patients receiving blood from donors aged younger than 20 years (HR = 1.12; 95% CI, 1.1-1.14) and blood donors aged 70 years and older (HR = 1.25; 95% CI, 1.08-1.44). In addition, recipients of blood from female donors had a greater mortality rate (HR = 1.07; 95% CI, 1.07-1.07). These associations were weakened but not eliminated when adjusting for number of transfusions with a linear term attenuated the associations. A nonlinear pattern of the association between number of transfusions and mortality was observed. The association between donor age and sex and patient mortality was eliminated in analyses adjusting to accommodate nonlinearity.

“Using the same analytical approach as in the Canadian study, we were able to replicate their findings with some variation in point estimates,” Edgren and colleagues concluded. “However, after adjusting more carefully for the total number of red blood cell transfusions, neither donor age nor donor sex was associated with patient mortality Assuming our approach is correct, these findings indicate that, with regard to recipient outcomes, either of these donor characteristics need be considered when allocating red blood cell units for transfusion.”

“We believe these data reinforce the importance of extreme caution in assessing epidemiologic analyses in this field given the tremendous clinical and logistical implications of false-positive findings,” they added.

In an invited commentary, Nareg Roubinian, MD, MPHTM, from the Blood Systems Research Institute in San Francisco, and colleagues wrote that these findings provide convincing evidence that the contradicting results from the two previous studies were likely due to differences in the statistical approach for controlling confounding.

“This conclusion also highlights the challenges and limitations of interpreting novel findings discovered by mining observational data rather than testing a priori hypotheses derived from biological mechanisms,” they added.

“In the end, we are optimistic that future efforts to understand health outcomes associated with blood transfusion will benefit from these types of studies,” Roubinian and colleagues concluded. – by Alaina Tedesco

Disclosures: Edgren and colleagues report receiving support from the Swedish Research Council, the Swedish Heart-Lung Foundation, the Swedish Society for Medical Research, the Strategic Research Program in Epidemiology at Karolinska Institutet, and the Danish Council for Independent Research. Roubininan and colleagues report no relevant financial disclosures.