The number of people suspected of killing themselves while patients at public hospitals has jumped by more than 500 per cent.
Figures released by the Health Quality and Safety Commission into serious and sentinel events in the 2011-12 year reveal 17 people were believed to have committed suicide while inpatients, up from just three a year earlier.
Commission chairman Professor Alan Merry says most of the cases involved mental heath patients although at least two were on general wards.
"There appear to be no common factors. There is also no evidence of a trend of increasing inpatient suicides," he said.
In 2007/08 16 suicides were reported, dropping to single figures in the following years before this year's spike.
Nine died while in a hospital, five were on approved leave, while three had gone missing from an inpatient facility.
The report also found that six patients went missing from mental health facilities and it said: "It seems possible there is an issue of supervision of patients that needs to be addressed by DHBs."
Overall, adverse events deemed serious or sentinel fell by 10 to 360 last year with falls (170) the main contributor.
Prof Merry says not all the events described in the report were preventable, but many involved errors that should not have happened.
"In some tragic cases errors resulted in serious injury or death."
There was a rise in the number of cases of delayed treatment, up to 17 from 13 a year earlier while the number of medication blunders had fallen.
Prof Merry says despite the fall in the number of adverse events there were still too many people being harmed.
"This is not about apportioning blame. This is about learning from our mistakes and making our health and disability services safer so patients receive the care they need, without needless harm," he said.
* Readers seeking support and information about suicide prevention can contact Lifeline's 24-hour telephone counselling service on 0800 543 354.