February 25th, 2014

Study Raises Questions About Transfusions in PCI Patients

A very large observational study raises important questions about the role of transfusions in PCI patients in the U.S.

In a study published in JAMA, researchers from Duke and Yale analyzed data from more than 2.25 million percutaneous coronary intervention (PCI) procedures at more than 1400 hospitals. The data came from the CathPCI Registry, a large ongoing study that includes  a significant proportion of all cardiac catheterization procedures in the U.S.

The overall transfusion rate was 2.14%, but there was a wide variation in transfusion rates across hospitals, ranging from 0 to 13%. A vast majority of hospitals (96.3%) had a transfusion rate below 5%, and more than a quarter (25.5%) had a rate below 1%. After accounting for differences in patient characteristics, the median transfusion rate was 2.5%.

As anticipated, transfused patients were older, more likely to be female, and more likely to have other medical conditions. In addition, they were more likely to have an MI, stroke, or death in the hospital; this association remained significant after adjustment for differences and regardless of bleeding events. However, transfusion was found to be beneficial in patients who had bleeds and preprocedure hemoglobin levels below 10 g/dL.

In the discussion of their findings, the authors note that “there appeared to be patients who underwent transfusion in the absence of clinical bleeding events and patients who underwent transfusion with nearly normal postprocedure hemoglobin values.” Transfusions, they write, “may have been driven more by local practice patterns than by clinical necessity.”

Along with previous findings from smaller studies, their results suggest that “further research is needed to clearly delineate the appropriate use of transfusion in patients undergoing PCI.”

In an email interview, the senior author, Sunil Rao, acknowledged that the study “is observational and thus has limitations inherent to all observational studies.” Asked about his own clinical practice in this area, Rao said:

Regarding our own practice, we routinely use bleeding avoidance strategies (appropriate dosing, targeted anticoagulants, radial access) in order to reduce the risk for transfusion post PCI. In patients who are stable post PCI (no chest pain, no active bleeding) we follow our transfusion protocol that recommends transfusion only if the hemoglobin is equal to or less than 8 g/dL(hct equal to or less than 24%). This is based on other observational data and as we mention in the paper, these data can be subject to confounding. So we really need randomized trial data to guide practice.

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