Another global analysis has highlighted the lingering gap in life expectancy between Kiwis and Australians. Why are we worse off than our neighbours? Jamie Morton explains.
First off, what is life expectancy, and where do we rank internationally?
Life expectancy's a measure of the average time we can expect to live, based on demographic factors like age, sex and others.
If we look at the commonly-used measure of life expectancy at birth (LEB), New Zealand's overall rates have been gradually trending upward over the last generation or two, according to StatsNZ data.
For instance, LEB for Kiwi males and females back at the mid-20th century was just 67.2 years for males and 71.3 for females – that gradually climbed to 76.3 and 81.1 years respectively at the turn of the century, and 80 and 83.5 years over 2017-2019.
The most recent LEB rankings of OECD countries put New Zealand in the middle of the pack, with an overall average of 82.1 years. That's ahead of the US, UK, Canada and Germany, but behind countries like France, Spain, Italy, Ireland and Australia.
Perched at the top are Japan (84.7 years), Korea and Norway (83.3), Switzerland (83.2) and Iceland (83.1).
Japan similarly topped the rankings in a new life expectancy analysis by the UK's Health Foundation.
"It probably largely reflects the much lower smoking rate by Japanese women and the healthier Japanese diet," Otago University epidemiologist Professor Nick Wilson said, "with particularly less red meat and less high saturated fat foods such as cheese and butter".
Didn't our Covid-19 response nudge our life expectancy higher?
The effect of circuit-breaking lockdowns and keeping viruses like the flu out for two years – saving perhaps more than 2200 lives in the process - indeed gave us a life expectancy bump.
A study that explored life expectancy in the US and 19 peer nations between 2019 to 2021 found that, while our average dropped from 82.36 in 2020 to 81.99 last year, that was still higher than 81.65 in 2019.
Along with Norway and South Korea, New Zealand was one of only three countries to gain life expectancy since 2019 – with other nations seeing large tumbles.
Considering New Zealand had recorded just over 50 deaths from Coronavirus until the beginning of this year, we're yet to see the impacts of virus-linked fatalities – now totalling 633 - on life expectancy.
Why does Australia have higher life expectancy?
The OECD's LEB rankings reported the life expectancy of Australian males at 80.90 years - and females at a world-leading 85.
That gap isn't new: and health researchers like University of Auckland epidemiologist Professor Alistair Woodward have been examining it for decades.
Back in 2000, Woodward co-authored a study that pointed to reasons like relative prosperity, social and cultural conditions and lifestyle factors like smoking and alcohol intake.
"There's definitely more than one reason – and one that stands out is we do worse with common cancers, both in terms of diagnosis and case fatality," he said.
Another 2018 study that analysed 15 years of data found how Australia had higher five-year survival rates across colorectal, lung, breast, prostate and melanoma cancers.
The Cancer Society said at the time that some 2500 Kiwi patients may have lived if they'd been living across the Tasman.
More recently, an Otago University-led analysis calculated five indicators of old-age structure to find that Australia had a better ageing structure compared to New Zealand.
It found that, until 2050, both countries would have an increase in the proportion of people aged older than 60, with people older than 80 years increasing by 200 per cent during that time.
Between 2000 and 2007, New Zealand women were 15 per cent more likely to die from cancer, while men were 5 per cent more likely than their Australian counterparts.
Australia also showed significant improvements in overall five-year cancer survival, whereas New Zealand had a minimal increase.
"We also know that chronic diseases that cause people to die in their middle and later life make a major contribution to the mortality burden," Woodward said.
Cardiovascular disease rates were notably higher in New Zealand than Australia, and cardiovascular disease mortality was also higher here across all socioeconomic groups.
Kiwis were less likely to receive cholesterol-lowering medication and some heart procedures like having stents fitted or coronary artery bypass surgery.
Woodward singled out another obvious factor: health funding.
"New Zealand has got a very efficient healthcare system, but we spend much less on it than Australia," he said.
"Even though Australia wastes, in my view, a good deal of what they spend, they still have better drugs, more machines, more doctors and more service capacity.
"That's reflected in better outcomes for things like breast cancer and bowel cancer."
Fellow Kiwi epidemiologist Professor Tony Blakely, now based at the University of Melbourne, said New Zealand had the highest life expectancy in the world up to around 1940.
"And then, around 1970, Australia pulled ahead and has been slightly above us since."
Blakely said Australia happened to move faster to address cardiovascular disease in the 1970s and 1980s, and, as Woodward noted, boasted slightly better health services.
Even migrants who moved to Australia after the war, and brought their healthier diets with them, could have made a difference to overall statistics, he added.
What's the deeper picture?
Both epidemiologists emphasised an unfortunate factor that helped set New Zealand apart: health inequity.
"If we stratify populations by ethnicity, there's actually very little difference between non-Māori and Australian life expectancy – or just a one-year gap," Blakely said.
"While Australia also has large health inequities, its indigenous people make up a much smaller percentage of the population."
Māori, in turn, accounted for 16.7 per cent of our population, according to 2020 figures.
Over 2017-19, LEB for Māori males stood at 73.4 years and 77.1 for Māori females; by comparison, non-Māori males are expected to live to 80.9 years, while non-Māori females are expected to live to 84.4 years.
Today, Māori health indicators showed striking gaps across almost all chronic and infectious diseases, as well as injuries: including suicide.
That inequity has been highlighted by the Covid-19 pandemic, showing a disproportionate number of Māori and Pacific patients among hospitalisations and deaths – and a lower rate of vaccinated people.
As University of Canterbury researcher Dr Matt Hobbs and colleagues wrote in The Lancet in 2019, inequity has been entrenched through colonisation, with its ramifications passed to current generations.
"Māori people have been politically, economically, and socially undermined, leading to lower income and life expectancy, poorer education and health outcomes, and stigmatisation within health care, among other consequences."
With renewed strides across the health sector to tackle the issue, Woodward hoped to see the divide narrow.
"Generally, we are doing better than we did in the past; and still not good enough by any means, but it's not all gloom and doom."