There are many many variables that go into making a final decision for a tx as everyone is so different. I am not a doc, but some of the criteria I am familiar with are: FEV1 less than 30%, pan resistant meaning resistant to many antibiotics, O2 dependency, heart health and the presence of pulmonary hypertension, arterial blood gas levels. These are only a few. They tend to like CF patients getting connected with a center at a "wellness stage" so they are not too sick to go through the process and they can be less stressed about the whole thing. As you know, when you are not feeling well and battling, that is a hard time to have to connect with a tx center. So, you can be referred well in advance of actually needing a transplant if your CF center is "good at the timing". That being said, you also don't want to connect too early when things are going fine and your numbers are stable since it is such a big step and some of those centers are very busy. Hope this helps.