If you think about it, we do, in fact speak of people’s or institutions’ finances as bein in good health or just healthy. This metaphor is in common use.
I you are looking for a literal way of saying it, however, the most obvious (albeit somewhat ugly) word is creditworthiness. the online Cambridge English dictionary gives the following definition.
The state of being creditworthy (= having enough money for banks to be willing to lend money to you.)
You can find examples of its use here: https://dictionary.cambridge.org/dictionary/english/creditworthiness.
So If you have failed to repay debt, or are bankrupt your creditworthiness rating will be very low. If, on the other hand you have high income and always make interest payments, your credit rating would be low.
The is a snag, of course. If you never borrow and never use a credit card, you will have no credit rating at all. That would be true whether you are a homeless person or a millionnaire who kept all your money in cash under your mattress. Perhaps, though, that is no different from a person who never goes to the doctor.
Now credit ratings have not always worked as they should. The ratings agencies went on rating banks at the top rating when we now know they were accelerating towards insolvency. But doctors are not (or not supposed to be) fallible or corruptible in that way.
This might be a more elegant word for what you have in mind.