Broadly defining people as "Asian" isn't good enough given Auckland's diversity, the Counties Manukau District Health Board says.
DHB chairwoman Lee Mathias said Statistics New Zealand data includes an "Asian" definition but health needs could differ widely between people who fit that definition.
"Subcontinent Indians have different needs to Fijian Indians. We have eight different groups of Chinese, all of whom have different needs. And that is challenging," Dr Mathias told Parliament's health select committee yesterday.
"Only this year have we managed to convince Statistics NZ that is not helpful for us to have "Asian": that doesn't help us plan our services."
Afterwards, Dr Mathias told the Herald that more than a third of Counties Manukau's population were defined as Asian, and that included second- and third-generation New Zealanders.
"[We want] a better breakdown of the various groups because the implications for us are around their health needs. And somebody from Hong Kong who has lived a middle-class life has very different health needs than somebody who has come from mainland China and possibly a small-village life."
Geraint Martin, the DHB's chief executive, who also presented to the select committee, said the Asian term did not help.
"It is just far too big and diverse. When we only had relatively small communities, perhaps it made sense. But now that [different ethnicities] are becoming such an important and such a large part of our population, we need to be more discriminating in how to capture data."
Kim Dunstan, a senior demographer for Statistics NZ, said detailed information on ethnicity was collected through the Census and other collection methods. Counties Manukau DHB could be referring to ethnic population projections, he said, which used the broad and overlapping ethnic groups of Maori, Asian, Pacific, European or other.
Mr Dunstan said a variety of practical limitations meant more defined groups weren't used.
"In time we would like to derive projections below those groups. For example, maybe Chinese and Indian, maybe Samoan in the case of Pacific.
"Producing the projections for those four broad ethnic groups is challenging. As the numbers get smaller and smaller, the complexity and difficulty in producing plausible and cohesive population projections becomes even more of a challenge."