The BBC's Kim Catcheside reports

They plan to establish the scale of the problem with a two-week study involving 200 health centres.

The move comes as Age Concern publishes a survey revealing that one in 20 people over 65 has been refused treatment by the NHS.

Sally Greengross of Age Concern: Lack of access to treatments younger people are getting

The charity says this is despite government assertions that treatment is based on need not age.

The survey also found that almost two million people have noticed different treatment from the NHS since they turned 50.

Prescribing concerns

The study of prescribing habits towards older people is being carried out by the Royal College of Physicians (RCP).

Medication for Older People, a 1997 report from the college, said older people were more likely to suffer from:

• Over-prescription of medicines
• Prescription of the wrong type of medicine due to misdiagnosis
• Poor monitoring of side effects and adverse reactions

The study will be repeated next year, and then both sets of data will be compared with evidence to see if doctors are prescribing in accordance with best practice.

The results will be used to encourage local improvements, the college says.

Complex process

Professor Stephen Jackson is leading the audit.

He said: "Prescribing is becoming increasingly more complex.

Older people felt they were denied some treatments

"This audit is the first time an attempt has been made to enhance prescribing on a national scale.

"We intend to enable both prescribers and older patients to benefit."

However, the study launches on the same day that Age Concern attacks the quality of NHS care for older patients.

In its survey, conducted by Gallup, Age Concern asked 1,597 adults over the age of 50 about their experiences with the health service.

They found that, of all health professionals, the respondents most commonly experienced problems with doctors.

The charity said: "Worryingly, many people cited GPs, the 'gatekeepers' of the NHS, as the main cause of their problems."

Criticisms of the NHS

Some comments Age Concern gathered included:

• "I was refused treatment because the money would be better spent on someone younger. It was a new treatment for cancer."
• "I was turned away for being over 65."
• "You tend to be fobbed off and told that it's just your age."
• "They don't respect you the same as younger people."
• "The NHS is not bothered about elderly patients."
• "They take less interest in you."

She said: "The 'don't care - won't care' attitude experienced by so many older people causes huge emotional and physical pain for the person on the receiving end.

"All older people should be entitled to the good quality healthcare which is currently enjoyed by the lucky few. The government should step up its action to improve standards nationwide. An audit of discriminatory practices is the first step towards achieving this.

"Older people and their families who want to speak out about unequal treatment should join our campaign; we will not be 'fobbed off' any longer."

Clinical reasons for restrictions

The British Medical Association said that rationing by age was unacceptable, but added that there was no evidence to suggest this was happening.

Dr Ian Bogle, the association's chairman, said: "This report raises very real worries in my mind because, generally speaking it is not a picture of the health service I would recognise."

He acknowledged that sometimes staff could be brusque, but said that on the whole they treated older people with respect.

He also said that sometimes the most clinically appropriate course of action would mean an older person being denied a treatment a younger person was given.

This was nothing to do with cost, he said.

"People should receive clinically appropriate treatment, whatever their age," Dr Bogle said.

"It will not always be the same treatment or referral. Cancers, for example, progress much more rapidly in younger patients than in older patients.