Appearing as part of an inquiry on government proposals to raise fees for drugs subsidised under the Pharmaceutical Benefits Scheme, federal health department acting deputy secretary Richard Bartlett disputed claims the changes would lead to some people failing to take their medications.

“I have no evidence to give an answer that says I expect it to have an impact on people filling their scripts,” Mr Bartlett said.

In a heated exchange, Greens Senator Richard Di Natale described Mr Bartlett’s testimony as “embarrassing for the department,” suggesting it was contradicted by the evidence from various studies. “We’re with the flat earth society here,” Senator Di Natale said.

Mr Bartlett’s testimony was at odds with that provided to the inquiry by several groups, including the Grattan Institute, which cited a review which found that of 19 studies from nine countries, all but two concluded that fees deterred people from taking their prescribed medication.

Mr Bartlett described the international evidence on the impact of such fees as “mixed”.

Under the proposals, which are estimated to save $1.3 billion over four years, fees for PBS medicines would increase by $5 per script for general patients and 80 cents per script for concessional patients, while the amount of money patients would have to pay for drugs each year before qualifying for safety net protections would also rise.

In its submission, the Pharmaceutical Society of Australia expressed concern that even as things stood, out-of-pocket health costs were so high that “there is a danger of patients foregoing some of their necessary medications due to cost”.

It cited a study which concluded that a 24 per cent increase in PBS fees introduced by the Howard government in 2005 had a significant effect on dispensing volumes for some medications, particularly for welfare recipients.

But Felicity McNeill, the first assistant secretary of the Pharmaceutical Benefits division said this study did not include drugs which cost less than the standard patient contribution. When these drugs were taken into account, dispensing volumes for many categories of drugs had actually risen after fees were increased, she said.

Mr Bartlett said the price of 55 per cent of PBS drugs, which represented 70 per cent of PBS scripts for general patients, would not rise because the price of these drugs was below the level of the current patient contribution. He said as a result of the proposed changes, the average general patient would pay $10 more a year for drugs, while the average concessional patient would pay $13.60 more a year.

He said the emergence of more expensive new medicines, along with the ageing population and greater rates of chronic disease were pushing up the cost of the PBS.

He said in 1991, the most expensive drug listed on the scheme was $843, while currently there are more than 500 drugs listed which cost between $1000 and $5000, and more than 50 that cost more than $5000 each time they are dispensed.