How we die changed in New Zealand

The register in 1911

New Zealand kept careful count of what killed its people long before it could do much about it. The Registrar-General published the numbers every year in the New Zealand Official Yearbook, in a table of principal causes that ran to about forty lines.

In 1911 that table recorded 9,534 deaths. Tuberculosis accounted for 738 of them, more than heart attacks and strokes combined in most districts. Another 1,156 came from the other great infections of the era, among them influenza, pneumonia, diphtheria, whooping cough, measles, scarlet fever, typhoid and infant diarrhoea. Heart disease accounted for 1,205 deaths and cancer for 809.

Those infections did their damage early. A country where one death in five is infectious is a country where a meaningful share of funerals are for children, and the Yearbook tables of the period carry separate lines for premature birth, congenital debility and convulsions of children under five.

The pandemic year

In 1918 the register nearly doubled. New Zealand recorded 16,364 deaths against about 10,500 in the years either side. Infectious disease accounted for 45 percent of them, the highest share in the entire record.

The Yearbook of 1923 set the numbers out with unusual bluntness. “During the latter part of 1918 the Dominion was visited by a most virulent epidemic of influenza of a character similar to that experienced in most countries of the world in 1918 or 1919,” it recorded. “The deaths from influenza alone during 1918 reached a total of 5,516, a number greatly in excess of the grand total for the preceding forty-six years, prior to which statistics of causes of death are not available.”

The same passage adds a caution that still applies to pandemic counting today. “The disease was more properly pneumonic influenza, and many deaths in the earlier stages of the outbreak were registered as caused by pneumonia, broncho-pneumonia, &c., which in the light of later knowledge would probably have been ascribed to influenza.” It also notes that the 5,516 figure “does not include Maori deaths—approximately 1,200—due to influenza.”

Influenza did not stop with the epidemic. The Yearbook’s own table shows it killed more people in 1919 and in 1920 than in any year before 1918.

When heart disease took over

The crossing came in 1922. For the first time, the register recorded more deaths from heart disease than from all infections combined, and it never crossed back.

Almost nothing had been cured by then. Penicillin was six years from discovery and twenty from mass production. What had changed was water, sewerage, milk, housing and the notification of infectious disease. Fewer people died young, so more people lived long enough to die of a worn-out heart.

Cancer passed infection in 1932 for the same reason. Cancer deaths were not climbing because the disease was spreading. They were climbing because the people who would once have died of pneumonia at forty-five were now reaching sixty-five.

By 1949 heart disease accounted for 37.5 percent of all deaths, the highest share any single group reaches anywhere in this chart. More than one funeral in three was a heart.

The cigarette decades

The middle of the century is where two curves cross in opposite directions.

Tuberculosis, which had killed hundreds of New Zealanders a year for as long as anyone had counted, collapsed. There were 666 deaths from it in 1950, 114 in 1960, 27 in 1980 and seven in 2020. Streptomycin, isoniazid, mass screening and better housing did in thirty years what public health campaigning had not managed in fifty.

Lung cancer went the other way. There were 206 deaths from it in 1950, 409 in 1960, 1,133 in 1980 and 1,792 in 2020. It is now the single deadliest cancer in the country, and it tracks the smoking habits of the generation that took them up during and after the Second World War.

The worst year on the roads

Accidents are the one group in this chart that rises and falls with policy rather than medicine.

Motor vehicle crashes were recorded against 238 deaths in 1950. By 1973 the figure was 837, the worst year New Zealand has had. Accidents of all kinds reached their highest count in 1977 at 1,763 deaths, about seven percent of the register.

Then compulsory seatbelts, drink-driving limits, better cars and better roads turned it around. Motor vehicle deaths were 508 in 2000 and 359 in 2020, in a country with twice the people and far more cars. Newswire’s road toll tool traces that decline year by year from 1921.

Peak heart

Heart disease reached its largest raw number in 1987, when 8,875 New Zealanders died of it. Its share of the register had already been falling for a decade, and after 1987 the count fell too. By 2020 it was 6,957, in a population that was substantially larger and considerably older.

That is one of the great unheralded achievements of modern medicine and public health together. Blood pressure treatment, cholesterol drugs, bypass surgery, stents, coronary care units and a long decline in smoking took a third off the leading cause of death in a single generation.

It also had a consequence. People saved from a heart attack at sixty do not become immortal. They go on to die of something else, later, and usually of cancer or dementia.

Cancer takes the lead

In 1998 cancer was recorded against more deaths than heart disease for the first time. It has led every year since, reaching 30.3 percent of all deaths in 2020 against 21.2 percent for heart disease.

Read carelessly, that looks like a cancer epidemic. It is closer to the opposite. Cancer’s rise in these figures is mostly the arithmetic of an ageing population and a retreating rival. Deaths have to be recorded against something, and when the biggest competitor shrinks by a third, whatever is left grows as a share.

Dementia

The fastest-growing group on the chart is the one the register could not even see for most of the period.

Dementia cannot be separated in the New Zealand data before 1979, and is understated until 2000. From there it climbs steeply, passing accidents in 2004 and stroke in 2016. By 2020 it was recorded against 2,890 deaths, nearly nine percent of the register.

Some of that is better diagnosis and a willingness to write dementia on a death certificate where a doctor would once have written old age or pneumonia. Most of it is simply that more people now live into their eighties and nineties. Newswire’s population feature When New Zealand turns old shows how far that has gone and how much further it has to run.

What changed in 2000

There is one step in this chart that is not a change in how New Zealanders die. It is a change in how deaths are written down.

In 2000 New Zealand moved to the tenth revision of the International Classification of Diseases. Among other things, it changed the rules for choosing which condition on a death certificate counts as the underlying cause, and it substantially reduced the number of deaths attributed to pneumonia. Deaths recorded as influenza and pneumonia fell from 1,197 in 1995 to 347 in 2000, a drop that appears in the Ministry of Health’s own published series as well as in this one.

Most of the long decline of infectious disease in this chart is real. The final step down at the year 2000 is mostly bookkeeping.

The whole century in one table

Decade	Deaths	Infection	Heart	Cancer	Stroke	Lung	Dementia	Accidents
1911 to 1919	97,216	22.9%	12.2%	8.3%	4.1%	2.5%	n/a	5.4%
1920s	114,629	16.6%	17.7%	10.7%	5.7%	2.7%	n/a	5.5%
1930s	128,000	12.4%	27.0%	12.9%	5.7%	1.6%	n/a	5.6%
1940s	156,495	9.9%	34.7%	14.0%	9.8%	1.1%	n/a	4.5%
1950s	194,258	7.7%	34.4%	15.7%	11.9%	1.7%	n/a	5.1%
1960s	228,418	7.0%	34.9%	16.5%	12.5%	2.9%	n/a	5.6%
1970s	251,068	5.3%	32.3%	19.7%	12.9%	4.4%	n/a	6.5%
1980s	265,189	5.3%	32.2%	22.8%	10.7%	5.5%	0.5%	5.3%
1990s	273,199	4.1%	29.4%	26.4%	9.8%	5.8%	1.4%	4.3%
2000s	282,558	2.2%	26.7%	28.4%	9.5%	6.1%	4.0%	4.0%
2010s	314,627	3.2%	22.5%	29.2%	7.8%	5.6%	7.0%	4.2%
2020	32,787	2.2%	21.2%	30.3%	6.3%	4.4%	8.8%	4.4%

Rows in brown are from the Official Yearbooks and count non-Maori deaths only. Rows from the 1950s are from the mortality collection and cover everyone. Lung means chronic lung disease, not lung cancer, which is counted under cancer.

What this chart does not tell you

Three things, and they matter.

The first is who is being counted. Until 1950 the Yearbook tables of causes of death covered non-Maori deaths only, and Maori deaths were tabulated separately and less completely. The step at 1950 in this chart is partly the arrival of about 1,500 deaths a year that were always happening and were simply counted elsewhere. Any comparison across that line is a comparison of two slightly different populations.

The second is that the groups are consistent in intent rather than in content. The century covers four revisions of the international disease classification, and each revision moved the boundaries. Grouping across them is a judgement, not a calculation. The groups here were checked against the Ministry of Health’s own published historical series for the causes both cover. Stroke agrees to within four deaths in every year from 1950 to 2013, and cancer to within two and a half percent. The heart grouping used here is deliberately wider than the Ministry’s, because it also counts rheumatic and hypertensive heart disease, which lifts it by up to a fifth in the earliest years and keeps it comparable with what the Yearbooks called diseases of the heart.

The chart starts in 1911 for a reason of its own. The Yearbook of 1930 records that “Since 1908, the classification of causes of death in New Zealand has been on the basis of the international classification initiated by Dr. Jaques Bertillon and used by the Commonwealth of Australia and the principal European and American countries.” Before that the register used an older English scheme of zymotic, constitutional and local diseases, whose categories cannot be matched to the groups used here.

The third is the end date. The most recent year in the internationally comparable series is 2020. New Zealand has kept registering deaths since, but the harmonised cause of death data that allows a like-for-like comparison with 1911 has not yet been published for later years.

A different kind of death

Put the whole chart in one sentence and it reads like this. In 1911 New Zealanders were killed by things that arrived from outside the body, quickly, often in childhood. In 2020 they were killed by the body itself, slowly, usually after eighty.

That is not a small change in medicine. It is a different relationship with death altogether. An infectious death was a sudden event that could take anyone. The deaths that dominate the register now are the ones that come at the end of a long life, and increasingly at the end of a long decline.

The infections have not gone anywhere. Covid-19 was recorded against 25 deaths in 2020, and the first line of the 1918 Yearbook table is a reminder of what a new respiratory virus can do to a register in a single spring. But for now, and for the first time in the history of this country’s record keeping, the thing most likely to be written on your death certificate is something you grew yourself.