The ACT's two health agencies use different datasets for the number of people who visit walk-in centres, but doctors are emphasising the need for "consistent, accurate data".
Internal emails reveal a discrepancy of more than 10,000 presentations between ACT Health and Canberra Health Services figures over a nine-month period.
ACT Health said there had been 93,246 presentations between July 1, 2023, to March 31, 2024, but Canberra Health Services said there were 104,533.
Australian Medical Association ACT president Kerrie Aust said it was essential the government had the capacity to provide consistent information about the health system, whether it's to clinicians, patients or taxpayers.
"I think it's reasonable to seek an explanation," she said.
An ACT government spokesman said the figures differed because "they were pulled from different systems which are used for different purposes".
He said ACT Health sourced the data from its "non-admitted patient collection" while Canberra Health Services sourced figures from the digital health record which is front-end operational data.
"There are some differences in the presentations that are counted for the purposes of funding (these include only patients who have been provided a service) and for reporting on total presentations to Walk-in-Centres from the perspective of the front-line clinic staff," the spokesman said.
These included counting patients returning to collect pathology results and counting patients who presented but left without being seen, or who did not wait to be seen by a nurse.
The spokesman also said "the reporting period for the two figures is different," adding that Canberra Health Services calculated presentations for nine more days in April.
Internal emails show an official said ACT Health's figure was more accurate as they were used for national reporting of data.
"My view is that the data from ACTHD is the cleansed and accurate data. Numbers we provide may be inaccurate due to patient inclusions which may not be correct," they said.
Lack of quarterly performance reports
The email exchange between officials in the agencies was revealed as part of a freedom of information request from opposition health spokeswoman Leanne Castley.
She pointed to the digital health record and how it prevented the collection of health data for several months while it was implemented.
"The huge divergence in walk-in centre figures also appears to be another case of the digital health record data not being reliable," Ms Castley said.
"There has been no published data on walk-in centre's in CHS' quarterly performance reports for nearly two years due to the ongoing debacle with the DHR."
ACT Health and Canberra Health Services were trying to get presentations data for Health Minister Rachel Stephen-Smith to be used in response to a motion being put forward in the Legislative Assembly about the walk-in centres.
No figures were given in the minister's speech.
The motion, from Labor backbencher Suzanne Orr, sought support from all parties to rule out a "politically motivated" review of the centres.
It follows recent revelations that health officials misled the public about the cost per service in the territory's walk-in centres by burying roughly $10 million in expenses.
Documents showed it costs nearly $200 per presentation but officials had previously told The Canberra Times it was "less than $110".
Officials had also said there were "more than 115,000 presentations" between January and December last year but newly released emails showed ACT Health recorded 113,095 presentations in 2023.
Government 'should not be afraid of audits'
Dr Aust said data about presentations to health services was used to make important decisions about allotting resources.
She said such discrepancies were the reason why doctors were calling for an urgent review of ACT's walk-in centres.
Candidates from the Independents for Canberra party David Pollard and Thomas Emerson have also called for such an evaluation after health officials gave inaccurate cost per service figures.
"This is a general issue right across the board where we need we actually need to know who's coming in, why are they coming? Are they being seen at the most effective and efficient part of the health system?," Dr Aust said.
She also said government should have data about how many people were being redirected to emergency departments or to their general practitioners.
It was revealed last month the government has been unable to measure redirections from walk-in centres to the hospital since November 2022.
"If we see signs that things are not accurate then we should be auditing [health services]," Dr Aust said.
"We should not be afraid of audits, they provide us with information that can be used to make our systems better."