Introduction

The CSO has a policy of careful and considered investigation of a data source before employing it to inform official statistics. However, as a result of the COVID-19 pandemic, the CSO began to explore experimental ways of obtaining up-to-date mortality data.

Due to the Irish custom of holding funerals within two to three days following death, these notices are usually placed in a fast and efficient manner, providing a valuable crowd-sourced means of tracking deaths. The notices are placed close to 'real time', the average length of time between date of death and publication is about 1.1 days. When compared with the statutory time limit of three months¹ for the registrations of deaths in the State, this is a timelier data source for monitoring trends in mortality.

The CSO published the first analysis of death notices using the website RIP.ie in July 2020. The initial analysis explored the use of death notices on RIP.ie to measure trends in mortality, finding a strong correlation between death notices and official CSO mortality statistics. In November 2020, subsequent analysis continued on this work, expanding the excess mortality analysis as well as updating the data to include 12 months’ worth of RIP.ie death notices.

Analysis of death notices was conducted as far back as 01 October 2019, to include the last month before the first global cases of COVID-19 were notified. This updated release covers the period October 2019 to November 2021 providing a full 26-month analysis of trends in mortality using death notices.

Measuring Excess Mortality

The COVID-19 pandemic has highlighted the challenges in obtaining timely statistics on mortality and, in particular, excess mortality (deaths over and above what would be expected under normal circumstances). Measuring the impact of such events on mortality trends can play an important role in policy and response efforts and in determining any additional impact on mortality related to the COVID-19 pandemic and its effects.

However, measurement of excess mortality is not straightforward. To most accurately measure excess mortality due to COVID-19 as part of this study, it would be necessary to clean and classify death notices on RIP.ie compared with the GRO for several previous years. Adjustments might be required for differing levels of expatriate usage, broadband penetration and controlling for potential changes in road traffic fatalities due to changes in vehicular activity and influenza deaths due to fewer personal interactions.

What is Excess Mortality and how is it measured in this report? Excess mortality measures the number of deaths over and above what would be expected under normal circumstances. Expected deaths are measured by calculating the average number of deaths for the same period in previous years. To get excess mortality we compare the deaths (or in this case death notices) in one period with the average of previous periods. In that sense excess mortality is an estimate.  In this release we look at a range of expected deaths (between one and three years prior) based on death notices published on RIP.ie. In some studies calculations of excess mortality look at an average of a greater number of years (e.g. a five year or 10-year average). Before 2017, the coverage of deaths on RIP.ie was not as comprehensive as in recent years and we observe that usage of RIP.ie steadily decreases as one moves backward in time. For this reason, if we were to use the RIP.ie data before 2017, it would increase the estimate of excess mortality for 2020/2021. Annual deaths are increasing over the last decade due in part at least to an ageing population. It is important to differentiate between this natural demographic effect and the effect of the pandemic. This is another reason to look at more recent years to establish expected mortality. It should also be noted that the calculation of mortality, including excess mortality, is based on deaths that occur in the Republic of Ireland. RIP.ie includes some deaths that occur in Northern Ireland and therefore these are removed. What can estimates of excess mortality can tell us? Estimates of excess mortality look at all causes of mortality during a period of observation, so the estimates of excess deaths are different to measurement of the number of deaths due to a particular cause (e.g. COVID-19 confirmed deaths). While COVID-19 confirmed deaths increased the level of excess mortality in the period, other causes may have had lower or higher impacts than in previous periods and none of these impacts can be disaggregated. Death notices, while having the advantage of timeliness, lack information on cause of death, and the age of the deceased, which is necessary to accurately profile mortality patterns over time. COVID-19 confirmed deaths include people who died with and of COVID-19, which results in a different period total to all cause excess mortality, though the peak months are the same in both measures. Another difference between the two measures – i.e., excess deaths and deaths involving COVID-19 – is excess deaths can be negative, where deaths due to COVID-19 cannot be. For example, six months of 2020 had less death notices than 2019. These months were January, June, July, September, November and December. When considered individually, these months had negative excess deaths in 2020 when compared to 2019.

Figure 2 examines monthly mortality figures by calendar year, with observed RIP.ie data forming the basis for cases from October 2019 to March 2021 and the remaining data coming from CSO mortality figures (discussed below). While there are observable seasonal peaks, there is significant variance year on year. A clear increase can be seen in the level of death notices observed in April of 2020 which contrasts with observed dips in mortality levels in April of all previous years. A total of 3,503 death notices were recorded in April 2020, which is over 900 higher than the next highest number of deaths recorded in April in any of the previous five years (2,594 in April 2018).

A simple method that has been used to calculate excess mortality gives a range of three different values. We calculate the death notices we would have expected to see during the period of March 2020 - February 2021 in the absence of the pandemic as:

1. The same as the number of death notices in the previous year
2. The average of the last 2 years
3. The average of the last 3 years

The expected numbers of death notices are subtracted from the observed numbers to arrive at the excess mortality.

Analysis of death notices for the period March 2020 - February 2021 (11 March 2020 was the date of the first reported death due to COVID-19 in Ireland) provides a range of estimates for excess mortality between 2,034 and 2,338.

Total Death Notices and COVID-19

The changing structure of deaths by gender over the period October 2019 to March 2021 can be seen by clicking on a month below:

Oct 2019 Nov 2019 Dec 2019 Jan 2020 Feb 2020 Mar 2020
Apr 2020 May 2020 Jun 2020 Jul 2020 Aug 2020 Sep 2020
Oct 2020 Nov 2020 Dec 2020 Jan 2021 Feb 2021 Mar 2021

Death Notices and Place of Death

The death notice often contains information about the place of death. For example, the death notice often indicates that the deceased died

• suddenly, at home
• in the tender loving care of the staff of a named nursing home
• unexpectedly, under the care of the doctors and nurses of a named hospital
• tragically, following an accident
• peacefully, at a named hospice
• on holiday, in a named foreign country
• at home, in a named foreign country

From the information in the death notice it was possible to compile the place of death for more than 80% of cases. It was also possible to identify a death on holiday, an expatriate (emigrant) death and the death of a citizen of Northern Ireland. Care was taken for deaths around the border between Ireland and Northern Ireland, as there are cases where it remains unclear which side of the border the deceased resided, despite the place of death. It appears possible that for those living close to the border, their funeral mass may be celebrated on one side, with burial on the other. Those dying on holiday have been classified as if they had died in Ireland, whereas Northern Ireland and expatriate deaths have been grouped together.

Often, the place of death was suggested or ambiguous, but not explicitly stated. For example, the deceased may have died 'surrounded by their loving family', without stating the setting. Another implication of the place of death was the suggestion of a donation to a named facility, e.g. hospice or community hospital patient comfort fund. However, these were often ambiguous, e.g. two or more donation recipients being suggested simultaneously. In the absence of an explicit place of death, notices were deemed to be other/unstated³.

Death Notices and Older Persons' Facilities

It was also possible to derive information on deaths in facilities for older people, (e.g. 'in the care of the staff of named facility'), most of which are registered with the Health Information and Quality Authority (HIQA). HIQA's Older People's inspection team are legally responsible for the monitoring, inspection and registration of designated centres for older people, such as nursing homes, in Ireland⁴. This analysis focussed on mentions of HIQA-registered older persons' facilities⁵.

Methodological Notes

To calculate excess mortality, we subtract the number of death notices we would have expected to see in the absence of the pandemic from the number of death notices we observed. 

Observed Death Notices

Each death notice pertaining to a date of death between 01 October 2019 and 31 March 2021 (the period under investigation) was read, cleaned and classified. Cleaning involves removing:

• Death notices pertaining to expatriate deaths
• Death notices pertaining to Northern Irish citizens
• Nulls – these are empty records which contain no information, a result of the web-scraping process
• Duplicates, which are so rare as to be negligible

Expected Death Notices

Expected death notices are calculated as the death notices we would be have expected to see during the period of interest in the absence of the pandemic. We calculated expected death notices in three different ways:

• The same as the number of death notices in the previous year
• The average of the last 2 years
• The average of the last 3 years

Excess Mortality and the Choice of Period of Interest

Our analysis covers the period beginning in March 2020, to account for the impact of Covid-19 as the first recorded death was 11 March 2020. We examined the periods March to June 2020 inclusive in our first release and March to September 2020 inclusive in our second.

For our period of interest in this release, we cover the months March 2020 to February 2021, which includes two peaks associated with COVID-19. It is preferable to avoid beginning a reference period around a peak of winter mortality where seasonality is observably established. Due to the novelty of this illness, it is not clear if there is a seasonal pattern of deaths associated with it or where it might peak. For example, Canada’s first peak of deaths attributed to COVID-19 occurred in May 2020 while Russia’s occurred in June 2020. To allow for this, we present three windows, noting that a period of interest cannot exceed 12 months.

1. We compare the period October 2019 to September 2020 inclusive with the same period in earlier years to remove the distortion brought about by winter mortality. This captures the effect of the first wave of deaths due to COVID-19 and incorporates the trough which followed it. 

2. In addition, now that 2020 has ended, we can show an estimate of deaths for 2020 for comparison with earlier calendar years, with the caveat described above. It should be further noted that the rise in deaths from one year to another is not automatically considered to be excess deaths. Indeed, the number of deaths annually, per calendar year, has followed an increasing trend since around 2010. Between 2010 and 2018, the average annual rise in the number of deaths was 397. The largest fall was 252, between 2013 and 2014. The largest rise was 875, between 2014 and 2015.

3. We continue the series released in July (March to June) and November (March to September) 2020, by showing a range of three values for excess mortality for the period beginning in March 2020 and ending in February 2021.

Analysis of death notices for the period beginning October 2019 and ending September 2020 provides us with an excess mortality range of 882 - 1,326. Further analysis was carried out to estimate the excess mortality for the 12-month period January - December 2020 provides a range of 283 and 637. This helps demonstrate the difference in choosing a different time period and the impact that this has on excess mortality estimation.

It took considerable resources to read the more than 55,000 death notices for the 18-month period under investigation. It was not possible to repeat the process for the previous five years, so another method was used. The web address (or webpage or URL) of each death notice on rip.ie is constructed using an incremental number. As the landing page allows one to search and sort by date, it was possible to reference these incremental numbers against the death notice publication dates and determine an index. The results of this exercise are below. Furthermore, the proportion of Irish death notices has been determined by multiplying this figure by the 92.2% calculated earlier. This is first shown for the usual calendar year of January to December, for the years 2015 to 2019 inclusive. This allowed us to compare the results against a similar exercise carried out by HIQA in July. They used the same data, but a different method.

While its application to earlier years assumes the distribution is uniform across time, the figure of 92.2% was arrived at through rigorously reading through every record for a 12-month period. As there was also an element of modelling to arrive at the independently calculated HIQA values, the values calculated in this method were considered to be acceptable. This exercise was repeated back to the beginning of October 2014 to align with the period under investigation.  

Comparison of Death Notices to Deaths by Occurrence

Deaths by Occurrence measure deaths by the date on which they occurred. Death notices were also analysed by date of death. At the time of writing, the CSO had published monthly deaths by occurrence up to and including December 2017. Furthermore, the CSO had published annual provisional deaths by occurrence for the calendar years 2018 and 2019. A monthly series of 24 months was constructed from the provisional annual data for 2018 and 2019, extending the monthly series of deaths from October 2014 to September 2019. The annual provisional figures were apportioned to months using death registrations with the General Register Office (by date of death) for the years 2018 and 2019. This was on the basis that this was the best indication available at the time of writing of a monthly distribution for the years 2018 and 2019. It is important to have an accurate monthly distribution as we are calculating an excess death notice figure for a period of months – in this case, the seven-month period March to September 2020.

Although the CSO deaths by occurrence are not being used to calculate excess mortality at this time, they are singular as an official benchmark to measure death notices against. As noted in the HIQA report, there is an undercount of death notices relative to deaths by date of occurrence the further one goes back in time. Reasons for this phenomenon may be explained by market penetration, regional variations, use of competing services, broadband usage and IT literacy. Other complexities ignored in this analysis are the different timing of the flu seasons in different countries and the mortality of expatriates, which could impact the proportion of expatriate death notices in different months. It is noted that the resulting expected death notices are lower than if we were to adjust for this undercount. Part of the discrepancy in 2018 and 2019 may be attributable to the fact that the annual data from which the months are derived, are provisional.

The ad hoc and experimental nature of this updated analysis is noted; however, death notices continue to competently track registrations, albeit with a mean lag of one day compared with a mean lag of 63 days for registrations.

For further COVID-19 related information go to the CSO COVID-19 Information Hub

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Footnotes

¹Registering a Death in Ireland

²The analysis of COVID-19 confirmed deaths by date does not include numbers for probable COVID-19 deaths (which are included in totals provided by the National Public Health Emergency Team). It was not possible to provide analysis of probable COVID-19 deaths by date. For full analysis of COVID-19 confirmed and probable deaths please see the COVID-19 Deaths and Case Statistics releases.

³Cases where the place of death was unclear or unstated have been combined with cases where the circumstances of death are potentially identifiable. These low-frequency instances include: 1) there were a small number of deaths at residential facilities for retirees of religious vocations that are not regulated by HIQA; 2) deaths due to accident; 3) deaths at residential facilities caring for people living with mental health issue.

⁴HIQA - Older People's Services

⁵Register of Older Person's Facilities (CSV download)

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