A widely shared tweet by Gabriel Scally on Wednesday 22 April draws attention to an Irish Times article about the difference in relative COVID-19 death rates across the island of Ireland, and claims that “the death rate for #COVID19 deaths in hospital (and for all COVID deaths) is 50% higher in Northern Ireland”.
Gabriel Scally is a public health physician, visiting professor of public health at the University of Bristol, and is currently president of the epidemiology and public health section of The Royal Society of Medicine.
The Irish Times article, published on 22 April, was written by Michael Tomlinson, emeritus professor of social policy at Queen’s University Belfast. Scally’s tweet and Tomlinson’s analysis was also reported in the Irish News.
Two graphs were prominent in the Irish Times article.
In the body of the article, Tomlinson writes that “the graphs show death rates per million of population for the North and the Republic and also hospital-based deaths. In both examples the Republic’s death rate is two-thirds that in the North.” This is emphasised in the article’s sub-heading which states that the “data shows the Republic’s Covid-19 death rate is two-thirds that in the North”.
Mathematically, if A is two thirds of B, then it follows that B is 50% larger than A. So Scally’s tweeted claim can be assessed directly alongside Tomlinson’s claim in his article.
For the purposes of this fact check, we examine two claims made on 22 April:
- (Tomlinson) The Republic of Ireland’s COVID-19 death rate is two-thirds of that in Northern Ireland. (Scally) The death rate for COVID-19 deaths is 50% higher in Northern Ireland than Ireland;
- (Tomlinson) The Republic of Ireland’s COVID-19 hospital death rate is two-thirds of that in Northern Ireland. (Scally) The death rate for COVID-19 deaths in hospital is 50% higher in Northern Ireland than Ireland.
- The first claim that the death rate for COVID-19 deaths in Northern Ireland is 50% higher than Ireland is UNSUBSTANTIATED as the only figures for COVID-19 deaths in Ireland are restricted to deaths of people who tested positive for COVID-19.
- While there is definitely a difference in hospital death rates north and south of the border, the second claim is also UNSUBSTANTIATED as the Ireland figure for positive test patients dying in hospital is not exactly comparable with the Northern Ireland ‘daily surveillance’ figure which also includes notified deaths of people with positive tests who died outside hospital (for instance in care homes). The population figures used in Tomlinson’s calculations are also not up-to-date.
What is a death rate?
The ‘death rate’ is the number of deaths in a particular population, scaled to the size of the region’s population (typically the number of deaths per 1,000 people per year). The scaling makes death rates comparable across regions (assuming the processes of registering and counting deaths is similar).
What is a hospital death rate?
The death rate of people in hospital as a proportion of the population – as opposed to the mortality indicator/ratios described above – is not a statistic that is readily available or widely reported in the UK or Ireland.
Instead, standardised mortality ratios are collected and analysed. These calculate the ratio of observed deaths of patients who have been hospitalised to predicted deaths in the region. Variations on the indicators can include both patients who die in hospital and/or those who die in the community within 30 days of discharge from hospital. Figures are published for English, Welsh and Scottish hospitals. The National Audit of Hospital Mortality (NAHM) uses the standardised mortality ratio methodology to analyse and display in-hospital mortality patterns across 44 publicly-funded acute hospitals in Ireland.
The annual report by the Director of Public Health (core tables) does not mention hospital mortality indicators. A 2015 report on Summary Hospital-level Mortality Indicator (SHMI) – Deaths associated with hospitalisation by the Health and Social Care Information Programme stated that the “Department of Health, Social Services and Public Safety in Northern Ireland [now called the Department of Health] does not currently publish any indicators on mortality associated with hospitalisation.”
Tomlinson’s calculations assume that the population of Northern Ireland is 1.8 million. NISRA’s latest mid-year population estimate for Northern Ireland (the 2018 mid-year figure published in June 2019) is 1.882 million. Northern Ireland broke through the 1.8 million population barrier back in 2010 and the estimate has continued to rise annually.
Tomlinson’s calculations assume that the population of Ireland is 4.85 million. The Central Statistics Office’s latest population estimate for Ireland (for April 2019, published August 2019) stands at 4,921,500.
Comparing COVID-19 deaths across Ireland
Mike Tomlinson’s graph tracks Northern Ireland Registered and Republic of Ireland daily COVID-19 deaths from 18 March up to 10 April. He charts cumulative figures.
In the article, Tomlinson explains that “readily comparable statistics are simply not available across the island of Ireland from the daily headline counts”. He suggests:
“But it is possible to do two things. The first is to use registered Covid-19 deaths for the North and compare these to the daily surveillance reports in the Republic, bearing in mind that the latter will be incomplete. The disadvantage of this approach is that the data for registrations in the North will be at least a week behind the daily reports, as shown in the graph.”
As outlined in a recent FactCheckNI article, NISRA recently started to publish weekly figures for deaths in Northern Ireland that mention COVID-19 in free-form text on death certificates.
The first such weekly report on 17 April found that there were 157 deaths mentioning COVID-19 on the death certificate that occurred in total up to 10 April (with those deaths registered by 15 April).
While the data published alongside that report originally only included weekly totals of registered deaths (based on date of death), Tomlinson requested and was able to chart the daily figures.
The Irish Central Statistics Office explain on their website that a Death Notification Form (DNF) must be given to a Registrar “as soon as possible after the death and no later than three months from the date of death”. There is a significant lag between the date of death and the registration of death. CSO say “an analysis of death data for Q4 2019 shows that the mean average number of days between the date of death and date of registration was 63 days while the median was 18 days.”
While the Registrar has asked that qualified informants register deaths as quickly as possible, and now allows submission by email or post, there also is a requirement that all COVID-19 related deaths must be referred to a Coroner and this may delay registrations.
There is no identical measure being taken in Ireland to match the NISRA figure for Northern Ireland COVID-19-related deaths (irrespective of testing).
The most stable figures available are published by the Irish Department of Health (based on information from the Health Protection Surveillance Centre). On April 10, there had been “287 COVID-19-related deaths in Ireland”, i.e. 287 people diagnosed with a positive test for COVID-19.
However, this figure does not include people who died from COVID-19 without a positive test and is not directly comparable with the Northern Irish statistic that it is charted against in the Irish Times article.
Comparing COVID-19 hospital-based death rates across Ireland
Tomlinson’s second graph tracks the ‘hospital-based death rates per million population’ from 18 March up until 20 April. He charts cumulative figures.
For this graph, he does not rely on the new weekly figures from NISRA (which stated that by 10 April, according to their death certificates, 109 people had died in hospital with COVID-19).
Tomlinson uses the daily figures of COVID-19 deaths published by the Public Health Authority (and since 20 April, published by the Department of Health instead) report the deaths of patients who tested positive for COVID-19 within 28 days of their death.
In their 17 April weekly update bulletin, NISRA explain:
The daily Northern Ireland Government updates (PHA’s COVID‐19 Surveillance Bulletin) provided by the Public Health Agency (PHA) count the number of deaths reported to the PHA where the deceased had a positive test for COVID‐19 and died within 28 days, whether or not COVID‐19 was the cause of death. PHA figures may not capture all deaths that occur outside hospital.
These daily figures for Northern Ireland include some patients who tested positive for COVID-19 and died outside the hospital environment (e.g., in care homes or hospices) and unlike NISRA’s retrospective hospital figures, the daily PHA statistics exclude people who were never tested for COVID-19 even though the virus contributed to their cause of death.
So the daily figures published in Northern Ireland are not specifically hospital-based deaths, though (during the period Tomlinson considers) it is likely that in order to be tested, most of the people had been admitted to hospital within 28 days of their death.
The Irish Department of Health publishes daily statistics (collated in an archive) about COVID-19 testing and deaths. As well as an overall number of new deaths of people diagnosed with COVID-19, a cumulative figure is published, and the number of deaths that occurred in a hospital setting.
Conclusion about the two claims:
1. (Tomlinson) The Republic of Ireland’s COVID-19 death rate is two-thirds of that in Northern Ireland. (Scally) The death rate for COVID-19 deaths is 50% higher in Northern Ireland than Ireland.
While the COVID-19 death rate in Northern Ireland (irrespective of whether a patient tested positive or was ever tested for COVID-19) can be provisionally calculated, no comparable statistic is available for the Republic of Ireland (which currently only counts deaths of people who tested positive).
Without a figure for the number of COVID-19 deaths of Irish people who had not been tested, the data do not exist to support the claim in Michael Tomlinson’s article in the Irish Times and the subsequent claim in Gabriel Scally’s tweet.
2. (Tomlinson) The Republic of Ireland’s COVID-19 hospital death rate is two-thirds of that in Northern Ireland. (Scally) The death rate for COVID-19 deaths in hospital is 50% higher in Northern Ireland than Ireland.
Tomlinson’s chart of hospital-based death rates compares the Northern Ireland figure for deaths with positive COVID-19 tests (not all of which occur in hospital) with the Irish Department of Health’s statistic for deaths with positive COVID-19 tests (only occurring in hospital).
While these figures are broadly comparable, they are not identical measures, and the proportion of non-hospital deaths in this Northern Ireland figure for positive tested deaths is not known, so no assessment can be made of its accuracy to support the ‘two thirds’ claim.
It should be noted that the population figures used by Tomlinson do not match the most recent estimates published by the two regional statistical agencies and inflate the Northern Ireland ‘per million population’ statistics by 4.6% and the Irish figures by around 1.5%.
Lack of comparable evidence
A more specific Northern Ireland figure for COVID-19 deaths in hospital is available from the NISRA’s new weekly report which breaks down deaths in hospital for people whose death certificate mentions COVID-19. However, this figure ignores whether or not the person had ever been tested for COVID-19. And no corresponding Republic of Ireland figure is available.
According to NISRA, up until 10 April, 25% of COVID-19 deaths in Northern Ireland (regardless of testing) occurred in care homes or hospices, while 69% of deaths happened in hospital. The subsequent report of deaths up to 17 April updates those proportions to 34% of deaths in care homes, 1% in hospices, 60% in hospital.
However, it is clear that even by using more up-to-date population estimates and accepting the differences Northern Ireland positive test deaths (mostly in hospital, some not) and Republic of Ireland figures for positive test deaths in hospital, there is a significant mathematical difference in death rates north and south of the border.
The total number of people who die in hospital due to a particular virus or disease is a function of many factors (including demography and age), which is outside the scope of Tomlinson’s article. But the different recording and reporting of COVID-19 deaths in Ireland and Northern Ireland is important.
With no figures for total deaths due to COVID-19 in the Republic of Ireland, it is difficult to make accurate comparisons across the border to judge the overall significance of the hospital death rates.
Tomlinson may be correct in saying that “the different approaches to tackling the Covid-19 outbreak are resulting in different outcomes” on either side of the border. However, the existing public statistics do not provide clear evidence of the size of the gap given their lack of comparability.
On 1 May 2020, FactCheckNI issued the following statement in regards to this fact check.