Optimal use of fingerprint for patient identification: which fingers to capture?

How many fingers and which ones should be taken to find a good balance between an effective process to distinguish two individuals, and a not-too-cumbersome process?
Several places are using right and left index.
I’ve heard that thumb and index are usually the most damaged fingers, and that the middle finger is a good choice (but less usual).
I’ve also heard that 4 fingers is optimal (e.g. right and left thumb and index), and that adding more fingers will not change so much the results.

Any suggestion?