Northland District Health Board has the country's fourth highest rate of potentially preventable deaths, according to Treasury figures.
However, Northland DHB bosses say the data is out of date and "not a source of data the DHB uses".
According to a recently released Treasury report - which quotes Health Ministry 2009 "amenable mortality" rates - for every 1000 people aged under 75 in the Northland DHB region, more than 1.2 deaths could have been prevented if health care was given more effectively or sought sooner.
Of New Zealand's 20 district health boards, Tairawhiti DHB had the nation's highest rate (1.8). The Lakes and Whanganui DHBs were the only other areas with higher rates than Northland.
Waitemata in Auckland had the lowest rate at about 0.7 per 1000.
The national average was just under 1 per 1000. Amenable deaths included premature deaths from infections, cancers, birth complications, injuries and chronic illnesses.
Northland DHB general manager Jeanette Wedding said Northland had a similar profile as Tairawhiti with similar health issues.
When asked whether the board was concerned about Northland's potentially preventable death rate, she said the data was out of date and "not a source of data the DHB uses".
Instead of the amenable mortality rate, the DHB focused on "Ambulatory Sensitive Hospitalisations" or ASH, which was more current, she said.
These were hospital admissions deemed potentially avoidable had community health services been better delivered or accessed sooner.
Northland's ASH rate was about 22.5 per 1000 people aged under 75, according to the Treasury report - seventh worst of the 20 DHBs.
She said several determinants of poor health for selected medical conditions which affected the ASH rate were outside the DHB's "sphere of control, responsibility and authority".
"Some of the determinants include deficiencies in housing, sanitation, water treatment and diet which can be directly related to low incomes and rurality."
Overall, New Zealand's amenable mortality rate declined from 2001 to 2009.
In 2007, it was slightly lower than the 31-country average for members of the Organisation for Economic Co-operation and Development.
The Health Ministry, which released the DHB comparison as part of a Treasury report on health policy options, said amenable mortality rates were "a key indicator of health system effectiveness and access to health care".
Tairawhiti DHB chief health official Jim Green said Gisborne's high rate of poverty and large Maori population played a significant role in the region's high amenable death rate.
"We have the most highly deprived population of any DHB in New Zealand, a factor which is associated with, but not completely related to the Maori population proportion in the DHB being the highest - and significantly higher than any other DHB."
Although the estimates were adjusted according to age variations in each district, they did not take into account ethnicity, sex and deprivation.