Last month, a 102-year-old man was charged over the alleged aggravated indecent assault of a 94-year-old woman at an aged care facility in Waverley, Sydney's east.
In September, the Morrison government announced a royal commission for aged care following a string of horrific revelations of old-age abuse and neglect in nursing homes.
A study published in Journal of the American Geriatrics Society found 28 people died from injuries inflicted by fellow aged careers in the 14-year period to 2013.
The vast majority of aggressors and victims (90 per cent) had a diagnosis of dementia, according to the data from the National Coronary Information System and coroners' files.
Senior author Professor Joseph Ibrahim, head of the Health, Law and Aging Research Unit at Monash University's Department of Forensic Medicine, said "we do not even know that well enough to know what to call it."
"There is a spectrum of views from 'this is a murder, this is a murder' to 'what do you expect a person with dementia living with someone else with a dementia to do?'"
Nursing home providers are required to report allegations or suspicions of abuse including unlawful sexual contact, unreasonable use of force or assault against who recipients to the Department of Health and the Police within 24 hours under the mandatory reporting framework of the Aged Care Act.
However, providers are not required to report suspected assaults if the alleged offender is a resident with a cognitive or mental impairment and care arrangements that are put in place to manage their behavior within 24 hours.
"This means that the most common types of resident-to-resident aggression incidents – those involving cognitively impaired residents – are never collated and publicly reported on," Professor Ibrahim said.
"So we have no way of knowing the scale and severity of the problem."
Dr Sarah Russell, a public health researcher and director of Aged Care Matters, said the discretionary clause was "outrageous."
"We need to collect this very important data" to better manage and potentially prevent aggression incidents, she said.
Minister for Aged Care, Ken Wyatt, said in limited circumstances, approved providers are not required to report alleged or suspected assaults to the Department of Health, but they must report them to the police.
But the discretionary clause allowing providers not to report some suspected assaults did not clearly distinguish between the Department of Health and the police. The Australian Law Reform Commission has also raised similar concerns about the need for clarification.
In 2017-18, the Department of Health received 4013 notifications of assaults. Of these 3773 were required to be reported under the Act and 3226 were recorded as alleged or suspected of unreasonable use of force.
Professor Ibrahim said these figures were "vanishingly small", amounting to one or two suspected assaults per home per year across Australia's 2700 aged care facilities.
"It does not sound plausible that they could be capturing them all," he said.
The study found that 86 percent of the aggressors were male and the risk of dying from injuries caused by fellow residents was twice as high for men as women.
Aggressors were more likely to be younger and more recently admitted to the aged care facility.
The violent acts often occurred in communal areas in large facilities with 60 or more beds, in the afternoon or evening, and most often involved a push-and-fall type assault.
"They might say" you're in my chair or my house, get out "and the other guy is thinking the exact same thing," Professor Ibrahim said.
"Staff are very frightened of intervening [in cases of aggression] and there are lots of times when staff get hurt. There's no simple solution to it, "he said.
Roughly 40 per cent occurred in bedrooms, often when residents mistaken another resident's room for their own.
"These people with dementia are only able to communicate with simple methods," he said.
"A lot of these situations can be averted with a consistent approach, good training and skill set among staff who understand what a person with dementia needs and an environment that allows them freedom of movement."
Lead author Dr Briony Jain said that without an intervention, an increasing number of nursing home residents will be at risk of being aggressive because of Australia's growing age population and increasing rates of dementia.
More than half of aged residents are diagnosed with dementia. By 2028 and estimated 589,807 Australians will have dementia. By 2058 that number will tip over one million.
CEO of Leading Age Services Australia Sean Rooney said the organization was engaging in a consultation process with the federal government to report system and believed there was scope for improving current practice.
"LASA believes that better support for providers and more research into best practice management of this issue is vital to developing effective solutions."
Mr Wyatt said the royal commission would provide an opportunity to fully understand the challenges and issues faced by the aged care sector now and in the future.
Kate Aubusson is Health Editor of The Sydney Morning Herald.