Red blood cells, in most countries, can be stored for up to 42 days, but numerous observational studies suggest that “older” blood may be harmful to recipients. In one of my favorite interviews, Nancy Heddle, lead author of the “INFORM study” (NEJM Oct 24, 2016) tells us why we shouldn’t worry!

Nancy Heddle

Nancy Heddle

Professor Nancy Heddle from McMaster University in Hamilton, ON joins me for a fascinating discussion on her recently published prospective, randomized, pragmatic, and HUGE study on the association of the age of transfused RBCs with in-hospital mortality. The study is called “INFORM,” and Nancy is the lead author. This is one of my favorite interviews!

Is “Old Blood” like Old Milk?

If you go into a grocery store to buy milk, you will notice that the grocers have placed the “oldest” milk at the front of the shelf, and the “freshest” milk at the back! Grocers are simply practicing a philosophy called “first in, first out” (FIFO) that minimizes the number of products that expire. Blood banks follow pretty much the same strategy with blood for transfusion (with some exceptions).

A number of years ago, scientists noticed that the appearance and other features of blood at the end of its allowable storage period (“shelf life”) was decidedly NOT the same as at the beginning! Structural, biochemical, and various immunologic changes were described, and quite frankly, it all sounded really scary! In response, a few randomized trials and many more observational, retrospective studies were published. The randomized trials failed to show much of an association between older blood and bad stuff happening, but were underpowered. The observational studies, on the other hand, definitely made blood bankers and clinicians alike worry that something bad was happening (but came with the usual warnings about making too many conclusions based on retrospective studies). The jury was out, and we needed help to resolve the differences!

INFORM, like several other recently published randomized studies such as “RECESS” and “ABLE” (references below), was designed to look prospectively at the issue and determine whether there was evidence that blood bankers needed to change practices. INFORM is the largest and most inclusive randomized study on this issue published, and Professor Heddle takes us through the philosophy, structure, and results of the study! I’ll give you a hint: Blood banks’ current philosophy works! There are still some questions to be answered, but this study goes a long way toward ending the “age of blood” controversy! Check it out!

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DISCLAIMER and DISCLOSURES: The opinions expressed on this episode are those of my guest and I alone, and do not reflect those of the organizations with which either of us is affiliated. Professor Heddle wants you to know that INFORM was funded by the Canadian Institutes of Health Research (CIHR), and her research group receives funding from Canadian Blood Services and Health Canada. I (Dr. Chaffin) have no relevant disclosures for this episode.

The images below are generously provided by Professor Nancy Heddle.

Heddle Slide 1: Blood Storage Lesion
Heddle Slide 2: State of Evidence in 2010
Heddle Slide 3: Research Question for INFORM
Heddle Slide 4: Study Design for INFORM
Heddle Slide 5: INFORM Enrollment
Heddle Slide 6: Demographics (showing randomized groups)
Heddle Slide 7: Histogram of Storage Times for Both Groups
Heddle Slide 8: Results Showing No Significant Difference
Heddle Slide 9: INFORM Conclusions

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