Excess mortality continues for March 2022, albeit not as high as earlier in 2022

Background

The COVID-19 Mortality Working Group has examined the latest provisional mortality statistics up to 31 March 2022, released by the Australian Bureau of Statistics (ABS) on 23 June.

We have compared the observed deaths to our ‘baseline’ predicted number of deaths for doctor-certified deaths (by cause) and coroner-referred deaths (for all causes combined).

We have also provided an indicative estimate of excess mortality due to COVID-19 only, for the months of April to June 2022.

Baseline prediction

Our previous Actuaries Digital article discussed in some detail how we have arrived at our baseline predicted deaths. In short, our baselines are set by extrapolating linear regression models fitted to standardised death rates (SDRs), which are then re-expressed as numbers of deaths. For the pandemic years, we have included different years to train the regression models:

• For 2020 and 2021, we have used the 2015-19 experience

• For 2022, we have:
  • used 2015-19 experience to set our baseline for deaths from respiratory disease and dementia, on the basis that 2020 and 2021 experience for these causes was materially affected by the pandemic;

  • also shown the average experience in 2020-21, for reference, when analysing mortality from these causes; and

  • used 2015-21 experience to set our baseline for deaths from all other causes and for coroner-referred deaths, on the basis that it is likely that the 2020 and 2021 experience more closely reflects a slow-down in underlying mortality improvement than the impacts of the pandemic

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 numbers of deaths in each successive year. 

Excess deaths to 31 March 2022

Figure 1 and Table 1 below summarise the results of the analysis. This article concentrates on the experience in 2022, but we have also shown the 2020 and 2021 results for context.

Figure 1: Weekly actual and predicted deaths in Australia – All causes

Table 1 – Excess deaths in Australia

For the month of March 2022, total deaths were 6% (or +800) higher than predicted. Almost half of the excess deaths were doctor-certified deaths due to COVID-19.  Other unspecified causes also made a significant contribution to excess deaths, as did coroner-referred deaths (which will include some COVID-19 deaths). 

For the first three months of 2022, total deaths were 13% (or +5,100) higher than predicted (January +19%, February +14% and March +6%). This compares with excess deaths of -4,500 for 2020 and +3,400 for 2021. Deaths were above the upper end of the prediction interval (i.e. above the 97.5^th percentile) for all but one week of 2022 so far. 

By cause, in aggregate for these three months:

• there were 2,954 doctor-certified deaths from COVID-19, representing around 60% of the excess deaths;

• doctor-certified deaths from respiratory disease continued to be lower than expected (down 7% or 210), noting that there are normally relatively few such deaths at this time of the year;

• doctor-certified deaths from cancer were close to expected, as has been the case so far throughout the pandemic;

• doctor-certified deaths from heart disease, cerebrovascular disease, diabetes, dementia, and other diseases were all higher than predicted (by between 5% and 13%, or a total of 1,800); and

• coroner-referred deaths were 9% (+450) higher than expected, noting that some COVID-19 deaths (such as when people die at home) will have been referred to the coroner.

Data included in the ABS article COVID-19 Mortality in Australia released on 23 June 2022 shows that, in the first quarter of 2022, there were 499 deaths in people who were COVID-19 positive at death but where COVID-19 was not the primary cause of death. This means that COVID-19 was a contributory factor in around one-quarter of the excess mortality from non-COVID-19 causes.

COVID-19-related deaths in April to June 2022

While the ABS provisional mortality statistics data is only available until the end of March 2022, surveillance COVID-19 deaths are available daily. Figure 2 shows the number of such deaths in each month of 2020, 2021 and the first six months of 2022 (note: we have estimated the number of COVID-19 deaths in the full month of June 2022 based on actual reports to 23 June).

Figure 2 – COVID-19 deaths in Australia, reported from surveillance systems*

There were 912 official COVID-19 deaths in 2020 (including 854 doctor-certified) and a further 1,402 deaths in 2021 (1,212 doctor-certified). To 26 June 2022, there have been 7,360 COVID-19 deaths and we estimate that this will rise to 7,600 by the end of June. Of these, around 3,580 are expected to have occurred in the three months to 30 June 2022 (where we have no provisional mortality statistics).

The ABS article COVID-19 Mortality in Australia showed that, since the Omicron wave, COVID-19 was not the underlying cause of death on an increasing proportion of death certificates mentioning COVID-19. Figure 3 shows a comparison of deaths ‘from’ COVID-19 versus those ‘with’ COVID-19, noting that, for the most recent months, a large proportion of deaths had not yet been registered (the estimated numbers of unregistered deaths are also shown). Figure 3 also contains a line showing the proportion of registered COVID-19-related deaths that were ‘with’ rather than ‘from’ COVID-19.

Figure 3 – A comparison of deaths ‘from’ COVID-19 to those ‘with’ COVID-19 (source: ABS)

The proportion of registered COVID-19 deaths with COVID-19 has continued rising in 2022, from 12% in January to 21% in April and 25% in May. A large number of deaths are still to be registered in May, so this percentage could change – hence, this point is shown as a preliminary estimate.

As such, we consider it reasonable to assume that from April to June 2022, around 22% of COVID-19 deaths may have been with COVID-19 rather than from COVID-19.  Therefore, we estimate that, of the 3,580 deaths reported from April to June 2022, around 2,800 may be due to COVID-19.

Our prediction model suggests that, without a pandemic, there would have been a total of around 43,900 deaths in the three months from April to June 2022.

Thus, COVID-19 deaths represent around 6% extra mortality over April to June 2022 (around 5% in April, and around 7% in both May and June). As we consider it unlikely that mortality from non-COVID-19, non-respiratory causes will be in line with our pre-pandemic predictions, given the higher-than-expected mortality in 2021 and early 2022, we think it likely that total excess mortality in that period will have been higher than 6%.

Figure 4 combines our preliminary estimate of excess deaths due to COVID-19 only for April to June 2022 with our detailed excess death estimates shown earlier, to reveal cumulative excess mortality since the start of 2020.

Figure 4 – Estimated cumulative excess deaths in Australia since 1 January 2020

Deaths from the Delta wave in the latter part of 2021 and the Omicron wave in early 2022 had fully eroded the negative excess deaths experienced earlier in the pandemic by early January 2022. Cumulatively across the pandemic, our conservative estimate is that Australia had experienced around 6,800 excess deaths by the end of June 2022. This represents an average excess mortality rate of about 1.5% over that time.

These impacts by year can be seen separated into excess deaths from COVID-19 and other causes in the table below.

Table 2 – Excess deaths separated into COVID-19 and other causes

COVID-19 deaths

Figure 5 – Weekly actual and predicted doctor-certified deaths in Australia – COVID-19

There were 377 doctor-certified deaths from COVID-19 in March 2022, compared with 839 surveillance deaths (462 fewer). We would not expect the numbers to be identical, because:

• there are delays between the time of death and lodgement of the doctor’s certificate (noting that we have not made any allowance for late reported COVID-19 deaths);

• the reporting criteria are different, with the main difference being that the surveillance reporting includes all deaths in people who have died while COVID-19 positive and without another clearly obvious unrelated cause (e.g. trauma), whereas the ABS deaths only include deaths where COVID-19 was the primary cause of death; and

• some COVID-19 deaths will be referred to the coroner (e.g. deaths occurring at home).

While COVID-19 deaths in 2022 have far exceeded deaths from this cause earlier in the pandemic, COVID-19 deaths in March 2022 were lower than in January and February.

Deaths from respiratory disease

Figure 6 – Weekly actual and predicted doctor-certified deaths in Australia – all respiratory diseases

In the four weeks of March 2022, deaths from respiratory disease were close to or lower than predicted, following the trend throughout most of the pandemic.

The following figures present a breakdown of respiratory disease into influenza, pneumonia, lower respiratory disease, and other respiratory diseases.

Figure 7 – Weekly actual and predicted doctor-certified deaths in Australia – influenza

There have been no Influenza deaths so far in 2022.

Figure 8 – Weekly actual and predicted doctor-certified deaths in Australia – pneumonia

Deaths from pneumonia in March 2022 have been fewer than predicted, and at the bottom end of the 95% prediction interval.

Figure 9 – Weekly actual and predicted doctor-certified deaths in Australia – lower respiratory diseases

Deaths from lower respiratory disease in March 2022 have broadly been close to predicted.

Figure 10 – Weekly actual and predicted doctor-certified deaths in Australia – other respiratory diseases

Deaths from other respiratory diseases continue to be close to our predictions in March 2022.

Non-COVID-19 and non-respiratory deaths

Figure 11 – Weekly actual and predicted doctor-certified deaths in Australia – all causes other than respiratory diseases and COVID-19

Excluding deaths from COVID-19 and respiratory diseases, deaths were higher than expected for three of the four weeks in March 2022, and above the prediction interval for two of those weeks. This is mainly driven by deaths from ‘other’ causes.

The following figures show a breakdown of non-respiratory/non-COVID-19 deaths into cancer, heart disease, cerebrovascular disease, diabetes, dementia, and all other causes.

Figure 12 – Weekly actual and predicted doctor-certified deaths in Australia – cancer

Cancer deaths continue to be close to predicted numbers for most weeks, albeit more commonly above than below. With diagnostic testing down in 2020, there were concerns that there would be a spike in cancer deaths in 2021 and beyond. While it is still early days, we are not yet seeing any clear evidence of this effect. 

Figure 13 – Weekly actual and predicted doctor-certified deaths in Australia – ischaemic heart disease

Deaths from ischaemic heart disease were again significantly higher than predicted in the first week of March, but close to expected for the remaining three weeks. 

Figure 14 – Weekly actual and predicted doctor-certified deaths in Australia – cerebrovascular disease

For cerebrovascular disease, deaths were close to predicted in March 2022.

Figure 15 – Weekly actual and predicted doctor-certified deaths in Australia – diabetes

Deaths from diabetes were also close to predicted in March 2022.

Figure 16 – Weekly actual and predicted doctor-certified deaths in Australia – dementia

Deaths from dementia were lower than predicted in March 2022, a reversal of the experience earlier in 2022.

Figure 17 – Weekly actual and predicted doctor-certified deaths in Australia – other unspecified diseases

Deaths from other causes, i.e. those not explicitly reported on by the ABS, were again much higher than predicted in March 2022. Three of the four weeks were higher than the upper limit of the prediction interval.

Coroner-referred deaths

Figure 18 – Weekly actual and predicted coroner-referred deaths in Australia – all causes

Coroner-referred deaths continued to be higher than predicted every week in March 2022 and were above the prediction interval for the last week of that month.

CPD: Actuaries Institute Members can claim two CPD points for every hour of reading articles on Actuaries Digital.