It’s all about the test: Counting COVID-19 deaths
by Allan LEONARD for FactCheckNI
14 April 2020
“The figures on deaths relate in almost all cases to patients who have died in hospital and who have tested positive for COVID-19. Slight differences in reporting in devolved administrations may mean that they include a small number of deaths outside hospital.” — Department of Health and Social Care (UK)
[This article is part of the COVID-19 Information Dissemination (COVID-19 ID) Project — a partnership between Community Development and Health Network (CDHN) and FactCheckNI. Its aim is to improve people’s health literacy about COVID-19 by providing accurate and up-to-date information which will increase knowledge, understanding and confidence and enable people to make good health decisions.]
Who is and is not being counted in this daily reported figure? What are the regional variations and why? We explain below.
Two main sets of COVID-19 data are regularly being produced:
- Daily reports on the deaths of people who had tested positive for the virus (mostly dying in hospital, though may include some people discharged to care homes); and
- Weekly reports based on the date and registration of death where COVID-19 is mentioned on death certificates no matter where the person died.
Only COVID-19 positive test deaths counted daily
Professor Chris Whitty (Chief Medical Officer for England) explained during a daily press briefing that DHSC figures include all those people who are proven to have coronavirus on testing. He also said that DHSC figures are collected the same way the whole time and are comparable to international figures, such as those published by the World Health Organisation (WHO), and represent “laboratory-confirmed cases” of COVID-19.
People who die elsewhere, such as in care homes or in the community, may never have been tested for COVID-19. This could be due to a lack of tests, or the lack of a test result before death, but in any case, a doctor may certify the cause or contributory cause of death as being consistent with COVID-19 symptoms.
Some people who tested positive for COVID-19 in hospital are subsequently discharged and later die out of hospital. Because there is an associated positive test, their deaths are included in figures from devolved administrations if their deaths have been reported back to the health authorities.
For those who were never tested for COVID-19 (or tested negative) and subsequently die, regardless of place, if a doctor deems that coronavirus was a cause of death and records it as such on the death certificate, that death will not be included in the DHSC daily figure but will be included in country’s registration of deaths data.
Daily reporting of COVID-19 deaths in Northern Ireland
The Public Health Agency (PHA) is publishing daily Surveillance Reports, which include the number of deaths of people in Northern Ireland reported to have died within a 24-hour period who had a positive COVID-19 test within the last 28 days (data correct up to 9.15am on the morning of the report being issued). This figure feeds through to the UK total and differs from the England & Wales figure in that it can include deaths outside hospital, for example, following discharge after treatment if these deaths are reported to the PHA. The daily PHA figure — which is sometimes updated as further information is made available — does not include any deaths where there was no COVID-19 test (or tested negative).
The Department of Health launched a COVID-19 dashboard on Sunday 19 April that will be updated daily that breaks down COVID-19 test results and deaths by council district as well as charting the availability and usage of Intensive Care Unit (ICU) beds.
Weekly reporting of COVID-19 deaths in Northern Ireland
The Northern Ireland Statistics Research Agency (NISRA) publishes figures on all registered deaths every Friday and refers to the week ending the previous Friday, a lag time of seven days. These are the definitive official statistics on the total number of deaths where COVID-19 is mentioned in free-form text on the death certificate. The figures remain provisional until the quarterly National Statistics are published, as there can sometimes be a delay in registration. Traditionally, these figures are based on the date of registration of the death, rather than the date of death.
From 17 April 2020, the NISRA weekly statistical bulletin on deaths registered in Northern Ireland looked at the date of deaths (not the date of registration). NISRA reported that up to Friday 10 April there were a total of 157 COVID-19-related deaths registered in Northern Ireland.
Information provided on death certificates allowed the place of death to be broken down as follows (for deaths up to 10 April):
- 109 people died in hospital (69%)
- 41 people died in care homes and hospices (26%) across 23 separate establishments
- 7 people died at residential addresses (4%)
A comparison between the PHA and NISRA reports is made in the following graph, showing end-of-week cumulative figures. PHA figures include anyone with a positive test for COVID-19, regardless of cause of death. The NISRA figures represent death certificates submitted to the General Registrar’s Office, with any mention of COVID-19 on the certificate, whether or not it was the primary underlying cause of death.
Figure: Comparison of COVID-19 positive test deaths and COVID-19 registered deaths, cumulative by week reported
These new figures reveal that up to week ending 10 April 2020 there were 39 — a quarter — additional deaths that weren’t detectable by the daily PHA reporting, i.e. people who hadn’t been formally tested.
The devil is in the detail of statistics:
- PHA’s daily figure of people who died in the previous 24 hour measurement period (up to 5pm the day before) and had tested positive is the most contemporary figure and comparable with other regions of the UK and internationally.
- The new weekly figure from NISRA based on date of death has been developed to allow backward comparison with PHA’s daily one.
- To compare the total numbers of deaths related to COVID-19, the most stable metric to use is NISRA’s weekly provisional death statistic, which is based on the date of registration of the death (rather than the date of death) and is less likely to have to be corrected due to late information. That statistic (table: Chart_2020) reports that 76 (17.5%) out of a total of 435 deaths registered in Northern Ireland in the week ending 10 April mentioned COVID-19 on their death certificate.
Other daily COVID-19 statistics
Every day at 2pm, the UK Department of Health and Social Care (DHSC) publishes the statistic for the number of people who have died of COVID-19, reported in the previous 24 hour measurement period (from 5pm to 5pm). This statistic is compiled from NHS England and Improvement, Health Protection Scotland, Public Health Wales, and the Public Health Agency (Northern Ireland).
Public Health England also updates a daily dashboard, which shows trends across the four UK countries on positive tests and deaths.
This daily figure is comparable with other countries’ metrics for those reported to have died and tested positive for COVID-19 in the last 28 days. The WHO publishes a dashboard of these data, which represents “laboratory-confirmed cases” of COVID-19 (i.e. does not include those who were not tested for COVID-19).
Other weekly COVID-19 statistics
Every Tuesday, the Office of National Statistics (ONS) publishes a weekly set of figures that show the total number of deaths in England and Wales (table: COVID-19 – Place of occurrence) where the death certificate mentions COVID-19 and which were registered in the week up to the previous Friday.
The National Records of Scotland (NRS) also produces weekly registered deaths every Wednesday for the previous week ending Sunday, a lag time of three days. In these data for deaths in Scotland, there is as yet no published data on place of death, beyond the NHS Board of usual residence. For the calendar year to date (31/3/2020), NRS reported 354 deaths where coronavirus (COVID-19) was mentioned on the death certificate in Scotland.
It is important to consider that there are two main sets of data in regards to counting the number of people whose death is attributed to COVID-19: (1) a daily figure of those who died who tested positive for COVID-19; and (2) a time-lagged figure of everyone whose death is attributed to COVID-19, regardless of any test. This second figure will always be larger than the first.
The two figures serve different purposes. As Prof. Whitty concluded: “The ONS data [registered deaths] [are] extremely useful for looking at the wider picture, but the [daily] NHS data [those who died who tested positive for COVID-19] is more useful for us to make decisions day to day and to make decisions, for example, about what we need to change, in terms of our current interventions.”
The original version of this article was published on 14 April 2020. This update references revised figures from the Public Health Agency and enhanced weekly data published by the Northern Ireland Statistics Research Agency.