I think it's an issue of determining competence. That's something that somebody with training can do, whether that training is as a physician, a nurse, or a nurse practitioner. As has been suggested by others, I think that if you're looking at judicial oversight of all this, or a legal framework for the final determination of the suitability of physician-assisted death, the health evaluation can certainly be done by others, not just physicians.
On February 4th, 2016. See this statement in context.