I think this page at the NMDP website is more up-to-date, and it too gives general statistics about the results of ATG treatment for AA:
http://www.marrow.org/PATIENT/Undrst...apy/index.html
In general, they report that a majority of patients respond to ATG and a majority reach survival milestones. They give several cautions about consulting your doctor when reading statistics like these.
Many generations of Americans had an attitude of "trust the doctor, don't ask questions, and don't expect answers" and many older patients still have that attitude, but things are different for the last generation or two. These days, patients often come to appointments armed with information and questions, and expect to participate in decisions about their care. The best doctors understand that this is for the better. While some doctors feel threatened, as if their expertise is being challenged, it's really an opportunity for them to share their expertise and benefit from the interactions and communication with patients.
Sometimes, even when all the facts are known, treatment choices have to be made for personal reasons instead of medical reasons, such as when you have to decide to live with a known condition or take a chance on a treatment that might help or might hurt. That can leave it up to the patient to consider quality of life and their personal goals. It's unfortunate, but sometimes these decisions are affected by practical issues over finances, insurance, ability to travel, and the proximity of the treatment center. Patients should have as much information as possible to make decisions about their treatment.
I hope the same change in attitude will come to Portugal. It varies quite a bit from doctor to doctor. If you can find any doctor more willing to talk, even just to you by telephone, that could do you a lot of good. Jorge is right to put his trust in you because you're looking for whatever information you can find to help him.