So, as I occasionally bang on about, I spend a fair bit of time with children and young people with cancer. We do a lot of transfusions of blood components in this population, frequently because we heartlessly pour toxins into them in order to try to kill of their malignancy.
We’ve been debating hard recently about the nature of these transfusions, and if a restrictive strategy should be used (using a lower level to trigger transfusion, and using less blood poured in.). It has been shown to be effective in critical care in adults and children but debate remains as to if it’s applicable outside this population.
What is the problem with different populations?
Well, put straighforwardly, it’s frequently NOTHING. There’s an instinctive dislike of change we all have and saying ‘it’s not from my backyard’ is a good and comfortable defense. But sometimes populations DO differ; but to suggest that this might be the case you need to explain WHY it is that your patients will have a different response to the intervention than those in the studies. (The malignancy argument goes: critical illness = normal marrow, relatively brief duration of illness, danger from large fluid infusions and shifts … malignancy = knackered marrow, year(s) of treatment, ability to manage fluid shifts.)
Then you need to look for differences between ‘your’ subgroup and others … such as this from the Cochrane review
And then … well. What do we do in the face of little evidence to guide practice?
(Hint – have a look here.)