More problems are being reported in New Zealand's hospitals, according to new analysis by a health watchdog, the Health Quality and Safety Commission.
Official figures on adverse events in hospitals show the number reported increased to 525 in the year to June, compared with 454 the preceding year.
There were just 181 in 2006.
But the commission said the increase was due to better reporting of incidents, rather than any increase in actual numbers.
The report said serious harm from falls was the most frequently reported event, with 277 cases, of which 84 caused a broken hip.
Clinical mismanagement was the next most serious category.
"Each one of these very sad incidents has affected a patient, their family and whānau, and the health professionals who care for them," said the Commission chair, Professor Alan Merry.
"While it is too late to prevent these particular events, we owe it to those affected to take a thorough look at what went wrong, so we can continue to improve systems and make care safer."
Professor Merry said the rise in the number of events reported reflected the culture change taking place in health care, with greater emphasis on learning from systems failings.
"DHBs, other health providers and the Commission are working together to help the sector better understand events leading to avoidable harm."
Hilary Graham-Smith of the Nurses Organisation said it was clear what was wrong.
"Staffing levels, workload and staff skill mix are contributing causal elements alongside patient flow and communication. At the end of the day positive patient outcomes and patient safety need to be the focus."
The story of Mrs X
The report outlined one case study in detail.
A 78-year-old woman, Mrs X, was admitted to the surgical ward for elective surgery. She had several long-term conditions, including diabetes, kidney disease and heart disease.
Her surgery went well and she was stable immediately after the operation. However, over the next two days she complained of breathlessness and chest pain, and her blood pressure became low.
Mrs X was seen by the cardiology team and thought to have had a heart attack. She was booked for a coronary angiogram - a heart artery dye test - later the next day. Her blood pressure continued to be low. As no clear cause was evident for her low blood pressure, no intervention was started for this as there were concerns that treatments could worsen some of her other medical conditions.
Mrs X was transferred to another ward before her angiogram. Following the angiogram, Mrs X was again moved to a different ward for observation. Her blood pressure continued to be low but was not noticeably different from her pre-angiogram blood pressure.
The importance of the slight difference in blood pressure from the admission baseline was not appreciated. Mrs X was therefore considered to be stable after the angiogram and was transferred back to the surgical ward where she was originally admitted. On return, the nurses noticed she was cold, clammy and confused in comparison to how she was on her admission a few days earlier.
Due to these concerns the emergency medical team was called. Mrs X was transferred to an intensive care unit and was found to have kidney failure. The prolonged period of low blood pressure may have worsened her existing kidney disease and Mrs X died.
A review of the case identified that the slow deterioration was not obviously apparent because of the specialities, wards and teams involved during the multiple transfers within the hospital. It was not until the return to the original surgical ward that the degree of deterioration was recognised.
In other details the report says more than a third of all the diagnostic mistakes involved delayed diagnosis or treatment, or wrong diagnosis or treatment.
It adds that problems occurred in private as well as public hospitals, and there were nine adverse events in ambulances and five in aged care centres, all of them involving falls.
The report also finds a number of recurring problems in several hospitals.
They include inadequate handovers between shifts or across specialties, poor communication with patients and their families, and information about patient deterioration not being recorded and communicated at handovers, either between shifts or across speciality areas.
The report recommends several improvements in training, communication and equipment in hospitals.