A future where baby boomer doctors all retire together and leave Canadians with a big hole in the supply of  physicians may not happen as predicted. 

A study, released Thursday by the Canadian Institute for Health Information, found that a third of physicians 65 and older are still working full time. Also, older doctors who were no longer classified as working full time still carried, on average, 40 per cent of a full workload. 

"This is the first time for this kind of study," said Geoff Ballinger, CIHI's manager of health human resources. "Staying 

In 2009, there were nearly 68,100 physicians working in Canada, one-10th of whom were 65 and older.

in the profession for a longer period of time helps dispel the perception of a shortage." 

Five years ago, nine per cent of Canadian doctors were over 65; today that figure is 12 per cent.

Doctors also feel that medicine is a calling and that you don't stop being a doctor at a certain age, he said. And, Ballinger noted, it takes so long to train to be a doctor that they start much later in their professions and so work later to have the same length of career as other professionals.

Thursday's study found that family doctors in particular are more likely to reduce their working hours than fully retire.

Historically, there is little information available on the retiring practices of doctors. Now that CIHI has gathered this data, it will help workforce planners to understand how many doctors will be needed.  "Now we know how many are easing out," Ballinger said. "Our urgency to replace them is not so great."

CBC's White Coat Black Art recently did a radio program on aging doctors. The host, Dr. Brian Goldman, explored the question, "when is it too old to practice medicine?" One doctor, Paul Friedman,  said ways to stay on top of the many changes include to teach residents and to work in group practices so as to be exposed to new ideas, medicines and technologies.

While the study, Putting Away the Stethoscope for Good? Toward a New Perspective on Physician Retirement, didn't ask doctors why they are staying on, Ballinger speculated that because family physicians are in private practice and self-employed, they are responsible for funding their own retirement. He noted that the equity and fixed-income markets took a dive a couple of years ago. 

While more doctors staying in the workforce after the standard retirement age helps with an ongoing doctor shortage, there are concerns about some of these doctors remaining competent and up-to-date with their skills. The study identified several doctors who are working into their 80s. 

The various provincial Colleges of Physicians and Surgeons do regular random assessments of all doctors. Ontario, for example, has a program of mandatory peer evaluations of all physicians over the age of 70. 

CIHI analyzed data from the 2007 National Physician Survey, the Scott's Medical Database, the National Physician Database and the Canadian Medical Association Master File.

with files from CBC's Mary Sheppard