Nine hospital patients in NSW have had to undergo further surgery after medical instruments were left inside them in 2015-16, a new report reveals.
The Auditor-General's latest report on NSW's health system shows there were 34 sentinel events - major adverse events that result in very serious harm or death to patients - in public hospitals in 2015-16, a third fewer than in the previous year.
"Even a small number of isolated sentinel events have the potential to seriously undermine public confidence in the healthcare system," the Audit Office said.
On top of the surgical instruments left in patients, nine patients committed suicide, six women died because of childbirth complications and four people died after being administered wrong medication.
Three patients either died or suffered brain damage because of intravascular gas embolism, where air bubbles enter the blood stream and block blood flow.
The report also recorded three deaths or major permanent loss of function due to operations on the wrong person or wrong body part. There were no cases of this type in the previous three years.
On average, one sentinel event occurred for every 85,893 patients admitted to a NSW hospital in 2015-16.
Opposition health spokesman Walt Secord said the data showed the health system was under "enormous pressure".
He demanded Health Minister Brad Hazzard to provide details around each sentinel event.
"The community only knows about the specific details when brave whistle-blowers or grieving families speak out," he said.
But a NSW Health spokesman said more than a thousand patients a day have surgical procedures and the rate of serious harm is low.
"The number of sentinel events has been stable over the last decade despite the increasing number of patients treated," he said.
"Of course, sentinel events should never happen, and to support this NSW public hospitals have a strong culture of identifying risks to patient safety and reporting incidents so improvements can be made."
Professor Jeffrey Braithwaite, a health systems researcher at Macquarie University, said it was extremely difficult to make inferences with very small numbers.
"So, sentinel events moving from 50 to 34, from 2015 to 2016, does not necessarily signify anything much when the numbers they refer to is so large," he said.
"This is a well known problem, where the denominator is very big and the numerator is small. So shifts from year to year are really not a good indicator of how well the system is performing."
The Auditor-General's report also said five "health entities", such as NSW Ambulance and Western Sydney, did not meet the Ministry of Health's performance expectations in the past financial year, up from three the previous year.
Even though NSW Ambulance met the ministry's target response time for imminently life-threatening incidents, its response times for potentially life-threatening incidents did not improve, remaining at about 11 minutes.
In addition, the rate of patients leaving emergency departments within four hours did not improve and NSW Health, on average, did not reduce the rate of unplanned hospital re-admissions.
Mr Secord called these "worrying trends".
He also criticised the government for changing the target to reduce the rate of hospital re-admissions to be less than or equal to 5 per cent.
Based on the old criteria, only one out of 15 local health districts (LHD) would have hit the target. Based on the new one, eight LHDs achieved the target.
The Auditor-General also underscored excess annual leave, overtime payments and "weak" timesheet approvals as shortcomings in the state's financial controls.
"Overall, NSW Health recorded an operating surplus of $407 million in 2016-17," the report said.
"Eleven local health districts/specialty networks recorded operating deficits ... four more than 2015-16," it continued.
"Expenses across NSW Health increased by 4.4 per cent ... lower than the expected long-term annual expense growth rate."