Fifteen people died in adverse events while in the care of the Bay of Plenty and Lakes district health boards last year, according to a Health Quality and Safety Commission report.
The Bay of Plenty District Health Board reported 25 adverse events in the 12 months to June - nearly twice as many as the 13 in 2017-18 and 15 the year before that.
The increase, however, could be the result of improved reporting systems.
The events included 12 falls and two healthcare-associated infections. In seven incidents, patients died and of those, five were classified as mental health events.
Lakes DHB reported 16 serious adverse events that included seven related to the clinical process, one fall and eight mental health events.
Five of the eight deaths recorded at Lakes DHB were classified as mental health events.
Serious adverse events are incidents that have resulted in a patient dying or suffering serious harm from using health and disability services.
Debbie Brown, the Bay DHB's senior governance and quality adviser, said when a person had an adverse outcome as a result of their care with the DHB, the adverse event was thoroughly reviewed and any resulting recommendations implemented.
"Last year we did a lot of work around falls and the harm reduction associated with falls and we are seeing the results of that this year."
Brown said the DHB was pleased with the decreased number of mental health events reported for the 2018/2019 year.
Lakes DHB reports 11 deaths among 21 adverse events
In a statement made on its website, Lakes DHB said while any harm suffered by patients was regretted, the DHB strived to learn from adverse events to reduce the risk of further similar events and to improve the quality of care by its teams.
Improvements made at Lakes DHB as a result of adverse events for the 2018-19 period included the establishment of a weekly combined diabetic/obstetric multidisciplinary team meeting to discuss all the pregnant women with diabetes.
A new audit process was to be implemented for radiology reporting.
Lakes DHB was also reviewing the admissions process for the mental health inpatient unit.
Across New Zealand a total of 312 deaths were reported to the commission in 2018/19, according to its annual adverse events report.
Of these deaths, 209 were suspected suicides reported from the mental health and addictions sector, and 103 were from across the rest of the health sector.
However, these deaths were not necessarily directly related to the adverse event.
International studies showed 10 to 15 per cent of hospital admissions can be associated with an adverse event, although about half of the events occurred before admission to hospital, in other health settings.
Some adverse events are known complications of treatment and not preventable.
Clinical lead for the commission's adverse events programme, Dr David Hughes, said data in the 2018-19 report indicated Māori were less likely to be reported as having had an adverse event.
"We are currently undertaking research into whānau Māori experiences of adverse events," Hughes said.
"We plan to use this research to develop recommendations for providers on how to better meet the needs of Māori who have experienced adverse events."
While Lakes DHB said it had not undertaken statistical analysis of this at a local level due to the numbers being too small to be statistically meaningful, of all events reported to the commission by Lakes DHB 11 involved New Zealand European patients, four involved Māori patients and one patient's ethnicity was "unstated".
Brown said Bay of Plenty DHB was starting to work on programmes around whānau Māori experiences of adverse events.
"Previously we didn't have good data around ethnicity of adverse events. But now we're including data in our reporting to the commission and starting to have a look at that data ourselves.
"That's something we are definitely focusing on."
Bay of Plenty DHB adverse events 2018-19
Clinical management (including maternity): 9
Healthcare Associated Infection: 2
Medication/IV fluid: 2
Lakes DHB adverse events 2018/19 period
Clinical process (including maternity): 7
Mental Health: 8
Source: Health Quality and Safety Commission