Revisiting the issue of disparity in Covid-19 death rates by ethnicity

 

10 Sept 2021: UPDATE   In our article (in Significance) discussed in the blog post below there was a misinterpretation of the WHO definition of 'age-standardized mortality rate'. It appears that the WHO definition uses age proportions based on its own international  'standard population'. While this makes almost no difference to the analysis of the ethnicity data in the paper, it does make a difference in the hypothetical example of North and South Bayesland. Specifically it means that the age-standardized death rate for South Bayesland is about twice that of North Bayeland and not as stated in the paper.  Thanks to Fridjtof Thomas (University of Tenessee Health Science Centre) for pointing this out.  The main conclusions in the paper are unchanged.

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Original post 16 April 2021

An article we first wrote in June 2020 has been published today in Significance magazine. It was triggered by an ONS report on Covid-19 deaths by ethnicity published in May 2020. For reasons possibly explained in our article, that ONS report is no longer available in its original form and the one now on the ONS website covering that period contains caveats and information that were not in the original report when we did our analysis. There was extensive national media coverage of the results of the original report, with every major newspaper and TV news channel in the UK focusing on the following highlighted conclusion:

"When taking into account age in the analysis, Black males are 4.2 times more likely to die from a Covid-19-related death and Black females are 4.3 times more likely than White ethnicity males and females". 

This information caused understandable fear and anguish among the Black community. But, when we analysed the report we found that there was insufficient data provided to support the conclusions and we also suspected that the ONS was basing its analysis on the 2011 census data which would skew the results (we wrote to the ONS asking them if this was the case, but did not receive a reply). Using publicly available data we showed that, while there was indeed a disparity, the death rate was likely to be about 2.1 times greater for Blacks, not 4.2 to 4.3 as claimed, and that when using the WHO defined measure to adjust for age there was little difference between Blacks and non-Blacks. We first published our analysis on ResearchGate in July 2020 and there was a widely read blog posting about it on 5 August 2020, which eventually led to the article's submission and publication in Significance today.

What is especially curious about this story is that at some point after we first published our analysis the ONS 'updated' their original report; in fact, even though the report is still dated 7 May 2020 they seem to have been continually updating the report, and the link which says Previous releases points to the National Archives where a search for previous releases draws a blank. In October we noticed that the report revised the difference in death rate between black and white males down from 4.2 to 2.9, and for females from 4.3 to 2.3 and this version specifically says it uses the 2011 census data. Looking at the report today it has been changed again. The original headline figures of 4.2 and 4.3 have been reinstated but critically the report now says:

After taking account of age and other socio-demographic characteristics and measures of self-reported health and disability at the 2011 Census, the risk of a COVID-19-related death for males and females of Black ethnicity reduced to 1.9 times more likely than those of White ethnicity.

There is also a later report dated 19 June with death statistics up to 15 May 2020 (rather than up to 10 April). This report says:

• This analysis showed that for all ages the rate of deaths involving COVID-19 for Black males was 3.3 times greater than that for White males of the same age, while the rate for Black females was 2.4 times greater than for White females.
• After adjusting for region, population density, socio-demographic and household characteristics, the raised risk of death involving COVID-19 for people of Black ethnic background of all ages together was 2.0 times greater for males and 1.4 times greater for females compared with those of White ethnic background.

What is clear is that the original figures, which were so widely seized on by the media, were exaggerated - as we originally said. And even the current figures are also likely to be exaggerated by failure to account for demographic changes since the 2011 census. Yet it is the figures in the original report that remain in the popular narrative and which have created an unjustified level of fear and anxiety among the Black community.

Fenton N. E, Neil M, McLachlan S, Osman M (2020), "Misinterpreting statistical anomalies and risk assessment when analysing Covid-19 deaths by ethnicity", Significance Magazine, April 2021