Whanganui District Health Board had the fifth-highest mortality rate in New Zealand in the 2010-11 year, according to figures released by the Ministry of Health.
The figures show 1.61 per cent of patients admitted to Wanganui Hospital died within 30 days of admission, a total of 156 people. This figure is the "standardised" rate that provides a fairer comparison than raw data.
WDHB's director of nursing and patient safety, Sandy Blake, said the DHB took mortality figures seriously.
"Chief executive Julie Patterson and I have put some important processes in place around when a patient dies," Mrs Blake said.
"We analyse the patient's notes and scrutinise the circumstances around their death to see if there's anything we need to be concerned about."
Mrs Blake said she understood the WDHB was the only one in the country that wrote to the family of every patient who died.
"The main purpose of this letter is to express our condolences to the bereaved family. But it's also to let the family know they can come and talk to us if they have any concerns about their loved one's death."
Mrs Blake said death was in some cases unavoidable, particularly in a hospital environment.
"We do provide a lot of palliative care, and it would be fair to say a lot of patients come to the hospital to die."
Mrs Blake said Wanganui Hospital serviced a community with a high proportion of elderly people.
"Wanganui does have an ageing population, and many of our patients are in their 80s."
The national standardised hospital mortality rate is 1.48 per cent, down from 1.68 per cent in 2006-7. In 2010-11, just under 8000 admitted inpatients and day patients died within 30 days of being admitted to hospital.
Waikato DHB had the highest standardised rate, with a rate of 1.78 per cent, while the Southern DHB had the lowest at 1.26 per cent.