Excess Mortality for 2023 Likely to Be About Half of 2022
Catch up on the Actuaries Institute Mortality Working Group’s latest analysis of excess deaths.
In summary:
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Excess deaths to 30 November 2023
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
For most weeks of August, September and October, actual deaths were close to predicted. However, deaths were much higher than expected for each of the four weeks in November.
Figure 2 shows deaths from COVID-19 and COVID-19 related deaths, noting that, given small numbers, weekly data for COVID-19 related deaths is not available for 2020 or 2021. (We have not requested our customised report from the ABS since July 2023, so the weekly COVID-19 deaths for the months of August to November are an approximation based on known monthly figures[1].)
Figure 2 – Weekly deaths from COVID-19 and COVID-19 related*
* COVID-19 data until the end July from ABS customised report 2023, approximation for August to November. Predicted COVID-19 deaths are zero as our baseline is intended to represent predicted deaths in the absence of the pandemic.
Deaths from COVID-19 and COVID-19 related deaths were low in August and September before starting to increase in the second half of October. COVID-19 deaths were high in November.
COVID-19 waves are very clear in Figure 2, showing an encouraging trend of reducing impact. However, it remains one of the leading causes of death in Australia and it is clear that there are lasting impacts for many who survive COVID-19 infection, including organ damage and Long COVID.
Excess deaths to 30 November by cause of death
Table 1 shows our estimate of excess deaths broken down by cause. We have shown the figures for the first eleven months of 2023 and the full year 2022[2].
Table 1 – Excess deaths in Australia – by cause of death to 30 November 2023 and for 2022
In the first eleven months of 2023:
- total deaths were 5% (95% confidence interval: 3% to 7%) or +7,400 higher than predicted;
- there were 4,235 deaths from COVID-19, representing 57% of the excess deaths;
- there were 1,349 COVID-19 related deaths included among the other causes of death, representing a further 18% of the excess deaths, while the remaining 25% of excess deaths (c. 1,800) have no mention of COVID-19 on the death certificate;
- deaths from pneumonia, lower respiratory disease and dementia were significantly lower than predicted (by between 8% and 19% respectively); and
- doctor-certified deaths from non-respiratory diseases other than dementia, and coroner-referred deaths, were significantly higher than predicted (by between 1% and 14%).
Deaths from influenza in the eleven months were also lower than predicted, but the very wide range of the confidence interval means that the difference is not statistically significant.
Lower than expected deaths from respiratory disease and dementia suggest that defensive measures are still providing some protection to aged care residents. If so, it is likely that deaths from COVID-19 are lower than would otherwise have been the case.
Figure 3 shows excess deaths (as a percentage of the predicted total) for each month of 2022 and 2023. We have shown the total excess (blue) and the contributions to that total of:
- deaths from COVID-19 and COVID-19 related deaths (orange), noting that Figure 2 showed that deaths from these two sources broadly move in the same pattern;
- deaths from respiratory disease (yellow);
- deaths from dementia (green); and
- deaths from all other causes (grey).
Figure 3 – Excess deaths (% of predicted total) by month in 2022 and 2023
COVID-19 deaths account for most of the excess mortality.
Deaths from respiratory disease have mostly been a negative contributor to excess mortality. The 2023 flu season was, like 2022, earlier than pre-pandemic normal[3].
Deaths from dementia are correlated with COVID-19 and respiratory deaths. Our Research Paper shows that a high proportion of deaths from dementia have either influenza or COVID-19 listed as a contributory cause, so it is no surprise to see the excess dementia deaths move broadly in line with COVID-19 and influenza waves.
Excess mortality from other causes (i.e., non-COVID-19, non-respiratory), somewhat follows the pattern of COVID-19 mortality. The correlation has been stronger in 2023 than in 2022.
Figure 3 shows that, in the months of August and September 2023, the small negative excess mortality was the result of lower than predicted deaths from respiratory disease and dementia, offset by higher than predicted deaths from COVID-19 and other causes.
Data and terminology
The Mortality Working Group has examined the latest Provisional Mortality Statistics, covering deaths occurring prior to 30 November 2023 and registered by 31 January 2024, released by the Australian Bureau of Statistics (ABS) on 27 February.
We have previously used additional data supplied by the ABS in a customised report in relation to COVID-19 deaths, namely the total number of deaths each week (doctor-certified and coroner-referred) both from COVID-19 and COVID-19 related, defined as:
- deaths from COVID-19 are deaths where COVID-19 is listed as the primary/underlying cause of death; and
- deaths that are COVID-19 related are deaths where the underlying cause of death has been determined as something other than COVID-19, but COVID-19 was a contributing factor mentioned on the death certificate[4].
We have not requested the customised report since July 2023 but will do so for our analysis next month, covering the full year 2023.
Baseline predictions
We calculate excess deaths by comparing observed deaths to our “baseline” predicted number of deaths for doctor-certified deaths (by cause) and coroner-referred deaths (for all causes combined). As always, our intent is for the baseline to reflect the expected number of deaths “in the absence of the pandemic”.
The derivation of our baselines and a fuller description of our methodology is documented in our Research Paper. 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. That means that our baselines allow for changes in the size and age composition of the population, plus the continuation of pre-pandemic mortality trends.
Disclaimer
This monthly COVID-19 mortality analysis is intended for discussion purposes only and does not constitute consulting advice on which to base decisions. We are not medical professionals, public health specialists or epidemiologists.
To the extent permitted by law, all users of the monthly analysis hereby release and indemnify The Institute of Actuaries of Australia and associated parties from all present and future liabilities that may arise in connection with this monthly analysis, its publication or any communication, discussion or work relating to or derived from the contents of this monthly analysis.
Mortality Working Group
The members of the Working Group are:
- Karen Cutter
- Ronald Lai
- Jennifer Lang
- Han Li
- Richard Lyon
- Matt Ralph
- Amitoze Singh
- Michael Seymour
- Zhan Wang
- Mengyi Xu
References
[1] The approximation uses the pattern of weekly doctor-certified deaths from COVID-19 in each month to spread the monthly numbers of deaths that are from COVID-19 and COVID-19 related.
[2] As in our previous work, we have estimated the number of coroner-referred COVID-19 deaths 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.
[3] We can see the impact of the early, lighter than average, influenza season in 2022 with a small contribution to excess mortality in June 2022, more than offset by high negative contributions in August and September 2022 (the months where influenza deaths usually peaked before the pandemic).
[4] The COVID-19 deaths covered in this article are distinct from “incidental COVID-19” deaths, namely deaths where the person was COVID-19 positive at the time of death, but COVID-19 was not recorded on the death certificate. These deaths are generally included in surveillance reporting where identified (other than where there is a clear alternative cause of death, such as trauma) but are not separately identified in the ABS statistics.
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