Transferring PhD programs after leaving a PhD due to medical issues
In the public and private R1 universities that I have been in, we do not accept transfers for doctoral students. If you're previously pursued a Master's or taken some graduate courses in the field as part of a doctorate at another institution, you can petition the department / graduate school for a partial waiver of some of the requirements after you've been accepted and matriculated into the doctoral program.

For example, you might be able to petition out of some of the breadth or depth core course requirements; or request that your years-in-residency be reduced.

Note that because many programs run students in cohort-years, there may be good reasons why you may elect to run the standard pattern even if you've had a waiver of some requirements.