Edith,
Physicians or medical researchers might have statistics about the evolution of AA to MDS (or to AML) but I haven't seen any recently. The studies that I've run across tend to be rather old.
This article from 2005 reported long-term evolution of AA to MDS at 10% to 12%, but those results were from studies that took place over 10 years ago. It may also differ by age group.
When an AA patient is later diagnosed with MDS, two questions are likely to come up:
- Did the AA evolve into MDS on its own or did the treatment for AA cause the MDS?
- Was it MDS all along? MDS, especially hypocellular MDS, can appear to be AA, so it's possible for MDS to go unrecognized or misdiagnosed.
Both questions are hard to study. Diagnoses are based on all available information at the time. It evidence of MDS wasn't originally apparent then it's hard to know later if it wasn't present or if it was missed. Researchers can look at past data but can't set up the usual type of double-blind study where some AA patients would receive the recommended treatment and some wouldn't.