Without proper costing information, former Australian Competition and Consumer Commission chair Allan Fels says there's not enough competitive pressure between providers to keep prices in check.
"A lack of informed choice means there is little competition between providers and excessive market power such that patients are worse off," Prof Fels wrote in his report into unfair pricing released on Wednesday.
The report cited evidence of overcharging, including Grattan Institute research that found out-of-pocket charges for specialists grew by more than fifty per cent in the decade to 2022.
This far outstripped wage increases in the same timeframe.
Prof Fels' report, commissioned by the ACTU last year, has revived calls to equip consumers with the information they need to dodge excessively high out-of-pocket healthcare fees.
Private Healthcare Australia chief executive officer Rachel David said most specialists set reasonable fees but the information asymmetry between them and their consumers was "massive" and could be exploited.
The body representing health funds wants more to be done to protect consumers, including publishing fees set by individual providers.
The Medical Cost Finder website was set up by the former Morrison Government specifically for this purpose but few doctors have signed up under the opt-in scheme.
Dr David said the government needed to intervene.
"The government has this data, they are just choosing not to publish it," Dr David said.
She would also prefer flexible referrals so patients can choose a provider rather than going to specialists named by GPs.
Consumers Health Forum of Australia chief executive officer Elizabeth Deveny said a nationwide healthcare literacy blitz would help solve many of the issues raised in Prof Fels' report.
"Whilst high out-of-pocket costs are a known barrier to accessing health care, fundamentally what we are also hearing from consumers is that the health system is so complex that they don't understand everything that Medicare entitles them to," Dr Deveny said.
She said the high cost of living was leading people to delay or go without healthcare entirely.
In his report, Prof Fels recommended reviewing specialist medical fees and the information imbalance.
The competition expert also advocated for something like the No Surprises Act in the United States to help protect consumers from bill shock.
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