Christchurch mental health patients - some deemed at high risk for violence - have escaped from locked wards more than a dozen times in the past two years.
Canterbury District Health Board figures released to The Press show mental health patients breached "the secure perimeter of a designated locked ward" eight times between July 2012 and September 2013.
The year before, there were seven such breaches.
All 15 incidents involved mental health patients who broke out of locked wards at Hillmorton Hospital and left hospital grounds.
All were eventually returned to care.
CDHB Specialist Mental Health Services chief of psychiatry Dr Sue Nightingale said while they were concerned over the breaches, the majority of people admitted to hospital for mental illness were not a risk to the community.
Two of those who escaped this year had been assessed as being "high risk for violence to others".
Nightingale said it was important to remember that the facility was a hospital, not a prison.
"Most people are here voluntarily and most of our wards are open and people are not confined to locked cells," she said.
"We are always concerned by any breach of security, but again, we have to balance people's rights to be treated in the least restrictive environment against the need to detain them."
The wards were only locked at night or when required for patient safety reasons, such as when there was a concern the patient may be at risk of harming themselves or others. "It is a hospital; they're not locked in their rooms," Nightingale said.
In each of the 15 cases, the patient had done something active, such as breaking a window, to leave hospital grounds.
Hillmorton also had "secure units" with locked doors, secured windows and secure fencing around the perimeter.
Only one of the incidents involved a patient escaping from a secure unit.
Mental Health Foundation of New Zealand chief executive Judi Clements said nationwide there had been a move away from secure units. "Locked doors and wards is a bit of an old fashioned way of looking at treatment. Now, we work more with increasing the . . . staff-to-patients ratio and having smaller treatment facilities to better treat people."
Patients had also occasionally absconded from Hillmorton Hospital while on escorted community outings or planned walks.
One patient was absent without leave from a non-locked ward for 10 days before being found and returned to care.
The trips were planned to "assist with community reintegration, benefiting the patient in their recovery," Nightingale said.
A police spokesman said they were routinely advised of any missing persons from the hospital and conducted enquiries to locate them, as they would with any missing persons case.
"If there are concerns about the safety of the missing person, or the safety of others, then we will respond accordingly."
- The Press