Bay of Plenty DHB chief operating officer Phillip Balmer said DHBs with lower amenable rates tended to "have a predominantly urban Pakeha demographic" who lived closer to hospitals.
"We believe our result is as expected but have in place a number of initiatives to ensure that we continue to improve in this area."
All deaths were reviewed each week by a panel of medical experts, Mr Balmer said.
Patient safety, clinical effectiveness and systems of care were examined in these reviews, he said.
According to the DHB's own figures, patient harm had reduced in several key areas in the Tauranga and Whakatane hospitals.
"We have seen a reduction of between 10 and 22 per cent [in patient falls] for the six moths till June," Mr Balmer said.
There had also been no "central line infection" since May 2010, which reflected a "reduced hospital-acquired infections" rate.
Patients were also less likely to miss doses of medication due to better documentation systems, he said.
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.
