Australia needs to rethink how it keeps sick, elderly people alive in hospitals and stop overtreating them at the end of their lives, the outgoing director of St Vincent's Hospital's Intensive Care Unit says.

Bob Wright, AM, a pioneer of intensive care medicine, said older patients are being treated more intensively and expensively than ever before and ''sometimes you wonder whether it's the right thing''.

Medical and legal experts have backed his call for greater discussion of the issue, warning that politicians and doctors are hamstrung by a system geared to save as many lives as possible.

New figures show over 65s are the most expensive age group to treat in intensive care, costing more than complicated neonatal cases.

Dr Wright, who retired recently from the position he held for 43 years, questioned whether it is worthwhile expending time, energy and money on elderly people who are beyond medical help.

''You can take someone who's young and dying and bring them back to life and then you've got someone who can live for another 40, 50, 60 years,'' he said.

He said elderly people who led active lives and were fit and healthy could still benefit greatly from intensive care, but there was a "spectrum" of doctors, patients and families who argued for vigorous treatment at the end of a life, even when the patient was ''irretrievable''.

Preliminary analysis provided to Fairfax Media by the NSW Department of Health shows it costs about $202 for every hour a person over 65 is in ICU, 71 per cent more than the cost of very young babies.

The number of people aged over 85 admitted to hospital surged 9 per cent a year in the five years to 2011-12, the most recent Australian Institute of Health and Welfare figures show.

University of NSW Professor of Intensive Care Ken Hillman said the issue was one of the most important facing the health system. "When we first established intensive care in the 1960s and 1970s we could keep people alive longer than we had previously, but … this gradual creep occurred, and we look at it now and think maybe this is something really perverse."

Professor Hillman said it was hard for politicians to talk about it because "everyone will say they are just doing it to save money". "If you think about the way that birthing changed in the '50s … The babyboomers need to change dying and death like they did with birth,'' he said.

Graeme Duke, an intensive care specialist at Box Hill Hospital in Melbourne, analysed data on more than 108,000 older Victorian patients and found ICU admissions for people aged over 80 rose more than 3 per cent a year over 12 years.

"I think it's probably related to better primary healthcare," he said. "This is a big quandary in modern healthcare: today's survivor may well be tomorrow's complex patient."

But he said he was surprised that his research, published this year in the Medical Journal of Australia, found that while people aged over 65 used an increasing proportion of ICU resources when they were admitted, their rate of admission was decreasing.

"It seemed to point towards … people getting better advice.''

In 2013 NSW Health Minister Jillian Skinner launched the advanced care plan, which includes a website that provides information on how to plan medical care.

Ben White, director of the Health Law Research Centre at the Queensland University of Technology, said some doctors were also hampered by legal concerns.

Australian Medical Association president Steve Hambleton said society needs to do a better job of end of life planning with the whole population. But he said that focus needs to steer away from cost of care, and placed on quality of life.