I suppose there were physicians who held doctorates for whom the term may have used, but from I have seen and read, the term was not generally used for medical practitioners until the 1700s. I see the term physician and surgeon a lot, but I don't see Doctor. If the term Doctor was actually used to refer to a person in their lifetime, great, include it as a prefix, but if not, I don't think we can assume that is was used for a physician or surgeon and therefore should not use it as a prefix.
See "Doctor (title)", Wikipedia: "The usage of the title to refer to medical practitioners, even when they didn't hold doctoral degrees, was common by the mid 18th century."
And "When Did Doctors Start To Be Called Doctors?" : "Around the 18th and 19th centuries, more people started using the term as universities began conferring the degree doctor of philosophy (Ph.D.). But, since there weren't many fields awarding a Ph.D., this became limited to professions like medicine, law, theology, and sometimes even music. . . . It was also in the 1800s that the field of medicine began to blur the lines between surgeons and physicians. And these physician-surgeons started to seek higher degrees and be called doctors. They wanted to get those MDs and earn that title. . . . What made things more complicated is that the general public started calling their healers doctors, regardless of any advanced degrees. As long as they were giving out medicine, even if they were pure surgeons without an MD, they were called doctor."