Matthew,
I'll give you my opinions as an experienced layperson.
I've heard the same 3-to-6-month estimate that you initially heard, so I'm puzzled about the recommendation to jump to another round of ATG without giving the initial round more time, especially if your mother's counts are lasting longer between transfusions.
The upcoming bone marrow biopsy, unpleasant as it may be, could provide useful information about the status or progress of the disease. That will also confirm for you that it's not MDS. Did your mother already have a BMB that ruled out MDS? If so, how long ago? I don't know how they'd be 100% certain of the diagnosis otherwise.
Be sure to ask for a copy of each biopsy report, and an explanation in layperson's terms.
It sounds like your family doesn't have a great rapport with the hematologist. If you can arrange for your mother to go to another treatment facility for a second opinion, you might get explanations that make more sense to you or, possibly, confirmation of reasons to go for rATG soon.
I wouldn't spend time worrying about whether naproxen and/or Covid-19 was a cause or a trigger for your mother's SAA. It really doesn't matter at this point. What matters is how to help her now, including whether side effects from current medications or lingering Covid-19 effects might be affecting her and complicating her ATG recovery.
It's natural to wonder what will happen if this or that treatment down the road doesn't help, but it can be very stressful to consider all possible bad outcomes, rather consider the current choices and concentrate on making the best decision for right now. It's true that about 1/3 of SAA patients relapse or fail immunosuppressive therapy (e.g., ATG and cyclosporin), after which transplants, other treatments, or clinical trials are possibilities. And 69 is no longer too old for transplants, especially for someone in otherwise good health. These days, many patients in their 70s are undergoing transplants with reduced-intensity chemotherapy. Yes it has risk, but that's to be weighed against other choices, not ruled out a priori.
You can learn more about SAA by contacting the
Aplastic Anemia and MDS International Foundation (800-747-2820,
help@aamds.org).