District health boards' days could be numbered.
Health Minister David Clark isn't ruling out scrapping the DHB model, which has been in place since 2000.
"We want to make sure we are the best health system in the world, and we compare relatively well to many of the countries we would compare ourselves to - we have a quality health system, and in many cases we provide care cheaper," he told Newshub Nation on Saturday.
"But we've got to look ahead 30 years - we've got a growing and ageing population, and we need to prepare for that."
He says DHBs presently duplicate many services, which could perhaps be done cheaper and more efficiently if they were centralised, and criticised the previous Government's freeze on hiring new administration staff.
"One of the alternatives is saying 'let's put a cap on administration' which the previous government did, and one of the consequences of that is you've got surgeons who are paid a phenomenal amount every hour writing their own case notes. There are perverse incentives."
There are also complaints about different service levels and pricing across DHBs.
"My gut feeling is we need to have a good, hard look at it," Dr Clark said of the DHB model.
"It is, until now, the best system anybody could think of. As I say, we do compare well to other countries. Part of having a detailed review is not throwing the baby out with the bathwater; trying to preserve the best we've got, but looking to the future with that ageing and growing demographic - more diabetes, more cancer and other expensive conditions to treat."
The Waipareira Trust has been fighting to get cheaper doctor's visits for west Aucklanders for several years, saying it's unfair those in the south get cheaper visits. Dr Clark agrees, but says he'll wait for recommendations from the reviews before making any drastic changes.
"It doesn't feel right to me… obviously with the Community Services Card holder changes coming in, that will make things better for many people."
The Waipareira Trust has also been encouraging west Aucklanders to visit the hospital when they're sick if they can't afford the cost of an after-hours medical provider such as White Cross, which can charge up $92 for a consultation.
The Waitemata District Health Board last year began giving vouchers to non-urgent patients so they could go to White Cross instead.
Dr Clark says that's "not how it should work", but acknowledged it's a pragmatic response to a health system that can't keep up with demand.
"I probably should be congratulating the DHB on actually taking the initiative of making sure people do get the health care in the setting they should get it in, rather than being critical.
The Government put another $4 billion into health in this year's Budget. Dr Clark says more and more of the Budget will be allocated to health over the coming years - it's already about 20 percent.
"As countries get wealthier they tend to spend more of their budget on health services because health is something that's incredibly important to everybody - without your health you don't have much - so I would expect that to gently grow over time."
There are presently 20 DHBs, who make decisions on how to spend money on health in their regions.