I WAS recently talking to a GP — newly returned to practice — who was back at the coalface in aged-care facilities. She was shocked by the unending list of drugs written on the medication charts for many of the high-dependency residents. Her instinct, she said, was to start withdrawing the drugs that looked the most pointless. It took the slightest pause before she added: “But what happens when they die and the family wants to complain ...”

It’s the rub that every doctor feels. The issues surrounding geriatric pharmacology are nothing new — age is a risk factor for disease and co-morbidity. As patients move through the health system they pick up more and more treatments from more and more doctors. Towards the end of last year I stumbled across this statistic: 55% of 65-84-year-olds have five or more long-term conditions. Even though I’ve been long exposed to all the stories of impending meltdown resulting from the ageing population, it still pulled me up short.

There are some questions that go to the core of medical care. One is the extent of the evidence base for actual overall benefits and risks when prescribing five drugs to a frail elderly patient. David Le Couteur, professor of geriatric medicine at Sydney University, suggests there is not much.

Part of it is wrapped up with the nature of clinical trials. The need to generate answers to whether treatments are effective means researchers want to use middle-aged patients with only a single disease. Throw in patients with multiple diseases on multiple medications and the confounding factors presumably maroon the research in a statistical no man’s land. It has been estimated that just 5% of randomised controlled trials are designed for patients older than 65.

The lack of robust clinical data echoes the problem faced by paediatricians when considering treatments for children. But there is one significant difference. We know the damage being done to the elderly population: the huge numbers of deaths and hospitalisations resulting from polypharmacy. One-fifth of elderly deaths in hospital are related to adverse drug reactions.

The lack of robust trial data on the risks and benefits of prescribing in the elderly exposes the clinical guidelines bombarding GPs for what they are — guidelines to treat specific disease that often fail to address the complex cases which the ageing population is making routine.

Professor Le Couteur and his colleagues go so far as to raise this question in a paper in press: “Does rational poly-pharmacy exist or does the evidence indicate that multiple medications are nearly always unethical?”

The rise in polypharmacy has no single cause — ageing does lead to disease, drug treatments have proliferated, big pharma likes to market its products as beneficial to ever wider groups of patients. But then there is the growth of defensive medicine. It is rooted in the code that it’s better morally, or perhaps legally, to cause inadvertent harm through doing something rather than inadvertent harm through doing nothing. The medical culture demands intervention, even in the face of evidence that intervention may risk serious damage.

The brave new world being sold to general practice through the coming health reforms is that GPs will become the key to dealing with complex chronic conditions — the conditions the policy makers have identified as the cause of sky-high hospital costs. The government’s approach will be to impose a list of clinical targets based on disease-specific best practice — HBA1C targets for diabetics, for instance. Then as an incentive they will start tying cash payments to GPs based on performance. But when geriatric pharmacology is so complex, this system looks nothing but dangerous, especially if it becomes blind to the fact that GPs are entering a clinical black hole.

Mr Smith isAustralian Doctor’s political editor.