Almost 20,000 excess deaths for 2022 in Australia

Baseline Predictions

Our previous Actuaries Digital article discussed in some detail how we arrived at our baseline predicted deaths. In short:

• Our baselines by cause of death are set by extrapolating linear regression models fitted to Standardised Death Rates (SDRs), which are then re-expressed as numbers of deaths.
• For our baselines by age/gender and by state/territory, we have used a slightly different, and more approximate, approach because SDRs are not available.
• Given the slight difference in approach, we end up with small differences in the total predicted numbers of deaths from our cause, age/gender and state/territory models, with increasing deviation as the projection period extends.
• Our models by cause of death remain the base for our “best estimate” of total excess mortality, as we believe that they best reflect the underlying mortality trends in Australia.

 

The baselines for our estimates of excess deaths remain “in the absence of the pandemic” for each of the three years 2020 to 2022.  We have not included any COVID-19 deaths in the baseline, as these would not exist in the absence of the pandemic.

As always, it is important to note that predicted death numbers are increasing faster from demographic changes (ageing and population size) than they are reducing due to mortality improvement. Therefore, our model predicts higher baseline numbers of deaths in each successive year. 

Comparison with ABS reporting

The results we present here differ from those quoted by the ABS in its commentary surrounding the release of the Provisional Mortality Statistics. The ABS explicitly states that the comparison presented is not an official estimate of excess mortality and that their baseline for 2022 (being the simple average of the number of deaths from 2017, 2018, 2019 and 2021, with no allowance for mortality trends or demographic changes) serves as a proxy for the expected number of deaths only. 

For example, the latest Provisional Mortality Statistics says: “In 2022, there were 174,717 deaths that occurred by 30 November and were registered by 31 January 2023, which is 22,886 (15.1%) more than the historical average.”  By comparison, we estimate that there were 17,900 (11.3%) excess deaths in this period. The main reason for the difference between the ABS figure of 22,886 and our estimate of excess deaths of 17,900 is the difference in the baselines used.

Excess deaths to 30 November 2022

Figure 1 shows the results of our analysis, comparing actual deaths each week to our predicted values and the 95% prediction interval.

Figure 1 – Weekly actual and predicted deaths – All Causes

Deaths in September and October, while higher than the predicted level, were within the 95% prediction interval for all but one week.  This is in stark contrast to earlier in the year when almost every week was well above the prediction interval (i.e. above the 97.5^thpercentile). In November, however, the last three weeks were again well above the upper end of the prediction interval.

Figure 2 shows deaths from COVID-19 and with COVID-19, noting that, given small numbers, weekly data for with COVID-19 deaths is only available for 2022. 

Figure 2 – Weekly actual deaths – Deaths from and with COVID-19*

Deaths from COVID-19 peaked in the last week of July, trended downwards until the end of October, and then rose again throughout November. Deaths with COVID-19 have followed the same pattern, although with a little more volatility given the smaller numbers of such deaths.

It is unclear how many people who died with COVID-19 would have died during this period anyway, and how many may have had their death hastened by COVID-19. However, given that with COVID-19 deaths follow the same peaks and troughs as from COVID-19 deaths, and that with COVID-19 deaths are only counted as such if COVID-19 is considered to have contributed to death, it seems that COVID-19 is a catalyst for with COVID-19 deaths, rather than being merely coincidental. We note that the same traditionally happens with the winter peak of respiratory disease deaths.

There may be instances where it is difficult to determine whether a death is due to COVID-19 versus COVID-19 being a contributing cause, and an element of professional judgment by the certifier will necessarily need to be exercised. It is unclear to us how often such decisions may need to be made, and how much “blurring” there may be between from COVID-19 and with COVID-19 deaths.  

Figure 3 shows the comparison of actual deaths to predicted after removing from and with COVID-19 deaths.

Figure 3 – Weekly actual and predicted deaths – All Causes excluding deaths From and With COVID-19

Even after removing all from and with COVID-19 deaths, significant excess mortality remains for 2022, with:

• A spike around the time of the January peak in COVID-19 deaths;
• another spike coinciding with the peak of the flu season (which this year came just before another peak of COVID-19 deaths) in late June; and
• indications of another spike in November when COVID-19 deaths were again on the increase.

Excess deaths to 30 November 2022 by Cause of Death

Table 1 shows our estimate of excess deaths broken down by cause. 

As in our previous work, we have assumed that coroner-referred COVID-19 deaths will be 5% of all COVID-19 deaths in 2022, based on the experience of late 2021 and the emerging experience in 2022. If our estimate of coroner-referred COVID-19 deaths is too high (or low), this will not affect the total level of excess deaths measured; it will just mean that our estimate of non-COVID-19 coroner-referred deaths will be too low (or high) by the same amount.

Table 1 – Excess deaths in Australia – By Cause of Death

For the first eleven months of 2022:

• Total deaths were 11% (or +17,900) higher than predicted, compared with excess deaths of -4,400 for 2020 and +2,900 for 2021;
• there were 9,360 deaths from COVID-19, representing 52% of the excess deaths and including 167 deaths reported as due to Long Covid;
• while not shown in the table, 2,592 deaths with COVID-19 are included among the other causes of death, representing a further 14% of the excess deaths and meaning that 33% of excess deaths (c. 6,000) have no mention of COVID-19 on the death certificate;
• despite influenza circulating in Australia again in 2022, doctor-certified deaths from respiratory disease continue to be lower than expected (10% lower) although not as low as we saw earlier in the pandemic;
• while doctor-certified deaths from cancer and dementia are close to expected in percentage terms (both 2% higher), these differences are statistically significant;
• doctor-certified deaths from heart disease, cerebrovascular disease and diabetes were all significantly higher than predicted (by between 8% and 17%);
• doctor-certified deaths from other unspecified diseases were also significantly higher than predicted (by 11%), continuing a trend observed since April 2021. Note that this is a large “catch-all” category and it is difficult to infer the reason for this large increase, although history suggests that non-ischaemic heart diseases probably make up more than 25% of deaths from other unspecified causes; and
• non-COVID-19 coroner-referred deaths were 7% higher than expected.

 

Excess deaths for the full year 2022

While the ABS Provisional Mortality Statistics data is only available up to the end of November 2022, we have formed an estimate of excess deaths in the month of December 2022 to arrive at a full-year estimate for 2022.

We have:

• taken deaths both from and with COVID-19 in the month of December 2022 from the COVID-19 Mortality in Australia article, making allowance for late-registered deaths;
• assumed that any contribution to excess mortality from respiratory disease will be negligible in the month of December, which is a summer month; and
• assumed that excess mortality from other causes of death would be the same as in the month of November 2022, i.e., about 5% of our baseline prediction.

 

This estimation process results in total excess deaths for the month of December of 14% of predicted, half of which (7% of predicted) are from COVID-19 and another 15% (2% of predicted) are with COVID-19.

For the whole of 2022, our estimate is that excess deaths were 12%. In other words, there were nearly 20,000 more deaths in 2022 than would have been expected if the pandemic had not happened. Of these, 10,300 were from COVID-19, with another 2,900 with COVID-19. The remaining 6,600 excess deaths were from other causes, with 1,500 fewer deaths than expected from respiratory causes and 8,100 excess deaths from other non-COVID-19 causes.

Figure 7 – Excess deaths per month in 2022 (including estimate for December) *

 

Excess deaths to 30 November by Age/Gender

Table 2 below shows our estimate of excess deaths by age band and gender. We have shown the excess including all deaths, and then again after deducting from and with COVID-19 deaths. 

Table 2 – Excess deaths in Australia – By Age/Gender*

Almost all age bands show excess deaths in 2022 (which is not all that surprising given the excess deaths for the whole population), but the number and percentage of excess deaths is higher in older age bands. The risk of mortality from COVID-19 is steeper than the underlying age mortality curve, so this result is somewhat expected.

However, it is notable that there are excess deaths in all age groups and that this excess is generally significant, even after removing COVID-19 deaths. To look at this further, we have shown these results similarly to the graphs by cause, showing weekly excess deaths by age band since the start of the pandemic. For these charts, we have been able to show the contribution of deaths from and with COVID-19 (in orange) separately to non-COVID-19 deaths. The 95% prediction interval is also shown. All age bands are shown using the same y-axis to give a sense of contribution of each age band.

Figure 8 – Weekly excess deaths in 2020-22 by age band (all persons)*

Figure 8 shows that excess deaths in 2022 are dominated by the older age groups. However, we already expect many more deaths in these age groups. It is instructive to consider the same information with the excess deaths expressed as a percentage of predicted deaths.

Figure 9 – Weekly excess deaths as a % of predicted in 2020-22 by age band (all persons)*

Figure 9 shows that the older age groups still experienced the most significant increase in excess deaths when expressed as a percentage of predicted deaths. Indeed, deaths of people over the age of 75 are significantly higher than expected in almost every week of 2022.

While the numbers of deaths in the 0-44 and 45-64 age bands are small, we saw in Table 2 that year-to-date excess deaths in 2022 are materially higher than expected. That table also showed that the percentage excess was higher for females than for males. The differences are worth investigation, although the small numbers mean that there is considerable natural variation.

Figure 10 – Weekly excess deaths as a % of predicted in 2020-22 for ages 0-44 and 45-64 by gender*

Figure 10 shows that female non-COVID-19 mortality experience in 2021 and 2022 is noticeably worse than male, especially in the 0-44 age band.

 

Figure 11 – Weekly excess deaths as a % of predicted in 2020-22 for NSW, Victoria, Queensland*

Figure 11 shows that these larger states all had better-than-expected mortality in 2020. It also shows the impact of the second COVID-19 wave in Victoria.

In 2021, Victoria shows a much higher level of excess deaths in the Delta wave – in the last quarter of the year – than either NSW or Queensland. A large portion of these deaths do not have COVID-19 on the death certificate.

In 2022:

• Queensland had a large peak in non-COVID excess deaths in the middle of the year (at the time of flu and COVID-19 waves). NSW had a smaller peak at this time, but Victoria did not have a similar peak; and

• barring the winter peaks for NSW and Queensland, Victoria’s non-COVID-19 excess has tended to be higher than the other two large states.

 

What could be causing the non-COVID-19 excess deaths?

The measurement of higher numbers of deaths than predicted does not tell us why this is occurring. There are several reasons hypothesised around the world (where this effect is occurring to a greater or lesser extent). It isn’t possible to identify from death counts alone what is causing the non-COVID-19 excess deaths, but we have listed below the most likely explanations. We note that multiple factors are likely in play, and different factors may be more or less pronounced at various times. 

To summarise the evidence from earlier sections:

• deaths with COVID-19 have followed the same pattern as deaths from COVID-19 in 2022;
• non-COVID-19 excess deaths have been highest when there have been peaks in COVID-19 deaths and peaks in influenza deaths;
• deaths due to some causes (dementia and “other” diseases in particular) are closely correlated to the level of respiratory disease (including COVID-19) circulating;
• non-COVID-19 excess deaths are particularly apparent in the oldest two age groups for both genders, and the youngest two age groups for females only;
• non-COVID-19 excess deaths are less apparent when there is no or little COVID-19 circulating, as illustrated by the difference between WA and the other states in early 2022.

A mystery partly solved?

One question that regularly crops up is why COVID-19 deaths reported by Victorian health authorities appear to be so much higher than those reported by NSW. The customised data that we have received from the ABS allows us to shed a little light on this, although some questions still remain.

The customised data that we have received from the ABS includes deaths both from and with COVID-19 for each of NSW and Victoria for 2022, with the deaths summarised into the week that they occurred. 

From the Federal Department of Health website we also have 7-day averages of the surveillance deaths reported by each state/territory health authority, summarised by the date the death occurred. The 7-day averages are reported in whole numbers only, but by multiplying by 7 we get an approximate number of surveillance deaths reported for each week of occurrence.

Per the national surveillance definition, deaths are reported as COVID-19 deaths if a person died with COVID-19, not necessarily because COVID-19 was the cause of death. Deaths are only excluded if there is a clear alternative cause of death that is unrelated to COVID-19 (e.g. trauma). As such, surveillance deaths will include deaths from COVID-19, deaths with COVID-19 and other deaths where the doctor/coroner has determined that COVID-19 was incidental and had no role in the death of the person.

By comparing the two datasets, we can estimate the number of surveillance deaths reported that do not end up with COVID-19 recorded on the death certificate.

Figure 16 shows, for each of NSW and Victoria, surveillance deaths expressed as a percentage of predicted deaths, broken down into those from COVID-19, those with COVID-19 and those where COVID-19 does not appear on the death certificate.

Figure 16 – Surveillance deaths as a % of predicted deaths

We can see that:

• deaths from COVID-19 are very similar for the two states, as a proportion of predicted deaths;
• Victoria has slightly lower deaths with COVID-19; and
• Victoria has significantly more surveillance-reported deaths that do not eventuate to have COVID-19 coded on the death certificate.

 

We do not have an explanation for why Victoria would record more surveillance deaths than NSW.