By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) - According to new guidelines being published in the Annals of Internal Medicine, the American Association of Blood Banks recommends physicians consider transfusing at a hemoglobin threshold of 7 to 8 g/dl.

Those numbers are not as important as the fact that there are recommended guidelines and they are not liberal. They want physicians to be more careful about blood transfusions.

A 20-member panel of experts looked at data from 1950 to 2011 to see what works best and avoid unnecessary transfusions.

The researchers examined things like overall mortality, non-fatal myocardial infarction, cardiac events, pulmonary edema, stroke, blood clots, kidney failure and many more areas. This is a great example of what we call evidence-based medicine, where decisions are made based on looking at large amounts of data.