Monthly figures for the department – currently embroiled in a data scandal – show in the past two years as many as 16 per cent of arrivals walked out after being triaged.

The emergency department's clinical director, Michael Hall, said the hospital's latest research showed about half the people who walked out did so through frustration because they had waited too long. "The numbers aren't what we want them to be," Dr Hall said.

"We think getting [the percentage of walkouts] to 5 or 6 per cent would be acceptable."

The hospital does not record why the vast majority of these people walk out but if its own research is used as a guide, it means at least 2700 people a year are leaving the emergency department because they are tired of waiting.

ACT Health says the number of hours these people spend in the emergency department is not counted in the emergency department's overall waiting figures.

One woman, former nurse Clare Knox, told the Sunday Canberra Times she walked out of the emergency department after waiting eight hours.

This was despite still experiencing a severe adverse reaction to medication. Mrs Knox, 68, said she asked that her reasons for leaving be recorded, but said she was told this was not the usual practice.

The Kambah woman said her long wait for treatment, which saw her walk out of the department at 3am one morning last September after arriving by ambulance, was traumatic. It was her only visit to the department in the past four years. "It was really cruel to ignore me," she said. Mrs Knox said she also complained to the hospital about what she said was incorrect record keeping. She said her records indicated her blood sugar level was taken at 9.15pm, while she maintained it happened an hour later. An ACT Health spokesperson said the directorate could not talk about her specific case for privacy reasons.

Opposition health spokesman Jeremy Hanson said her complaint could have alerted the ACT government to the data scandal earlier, if the protocol breach had been properly followed up. "You've got an extraordinary number of people simply giving up," Mr Hanson said.

ACT Health figures show the walkouts for the past year have averaged 9 per cent. In the previous year it was slightly higher with 12 per cent. The worst month was February last year, when 16 per cent (773 patients) left without being seen by a doctor.

The ACT Auditor-General's office recently found as many as 11,700 of the department's presentations were deliberately manipulated between 2009 and this year to improve overall performance information and reporting of the emergency department.

The hospital's executive director of critical care, Kate Jackson, has admitted that in 2010 she began tampering with the department's electronic files to improve waiting time results. Now nobody knows what the true waiting time results are for the city's largest emergency department. The department has just experienced its busiest fortnight ever with 2721 patients through in 14 days, or between 185 and 210 a day.

Meanwhile, department staff were being hampered by delays in other wards, according to Dr Hall. Between 30-50 per cent of patients to be transferred from the department to another ward wait up to eight hours for a bed and spend this waiting time in the department, he said.