The more blood needed to be added to a patient the higher chance of death. Researchers surprised that it only st a 1:1 ratio and not steeper.
Medical vs surgical patients had slightly different outcomes based on initial sicknesses / damage to the body.
From Clinical Anesthesiology.

“As anesthesiologists in the OR [operating room], we were giving coolers and coolers of blood, and we often wondered whether the patients survived their hospital stay,” Dr. Frank said. “We didn’t know the outcomes because we only dealt with OR. We decided to see if they survived, and also looked at the relationship between blood dose and in-hospital mortality. Perhaps more importantly, we also looked at five different morbid events,” he explained. We also wondered whether there was a point at which it becomes futile to continue giving massive transfusions,” Dr. Frank added. “It turns out the answer is no. A 50% survival rate is pretty good compared to other conditions, such as pancreatic cancer surgery, where the survival rate is about 20%. We don’t see a point of futility, and our recommendation is not to give up.”

“This is an important paper,” concluded Dr. Papadakos. “It shows that you get 50% mortality after giving 50 units of blood.” He added, “I’m surprised that it’s that low.”