Health care researchers and analysts are debating what, if anything, to do about this tide of aging practitioners. “We know that human faculties decrease with age,” said Dr. Mark Katlic, the thoracic surgeon who founded Sinai Hospital’s program.

Declining vision, hearing and cognition can affect any health professional (or any human). But Dr. Katlic has expressed particular concern about surgeons, who need to retain exceptional vision, manual dexterity, reaction speed and stamina.

Past age 70, “can you grab a tiny little blood vessel with a forceps and not grab something else?” he asked. “Or use very small instruments for sutures?” Some operations, he pointed out, go on for six or seven hours, even longer.

Studies haven’t produced clear-cut answers to such questions. Cognition and other abilities decrease with age — but the variability between individuals increases.

At 75, “there are sharp, wonderful doctors, and those who need to stop,” said Dr. E. Patchen Dellinger, lead author of a review on aging physicians published in JAMA Surgery.

Whether older surgeons have poorer outcomes than younger ones also remains debatable, because decades of experience and judgment can compensate for modest physical or cognitive declines.

One large study of Medicare patients found surgeons over age 60 had higher mortality rates for several kinds of operations, including coronary bypasses, but not for other procedures. And the differences were small, occurring mostly among doctors who performed few operations.