I’ve conducted a time-to-event analysis (accelerated failure time) for a research project, looking at the effect of an intervention on the probability of needing a blood transfusion during surgery. Instead of time however, I’ve used blood loss (in milliliters) as a proxy variable for time to event.
Everything I have read suggests that this is statistically valid (as blood loss increases, eventually everyone will need a transfusion- similar to as time increases everyone will experience disease progression or death, for example). however I can’t find any references where anyone has used an approach like this.
Curious if anyone has heard of this creative use of survival analysis before or could point me to a reference
I’ve determined that CPH assumptions were violated (the hazard of needing a transfusion increases with increasing blood loss, for example) and used an accelerated failure time model. Everything seems to check out