Factors associated with excess all-cause mortality in the first wave of COVID-19 pandemic in the UK: a time-series analysis using the Clinical Practice Research Datalink
Authors: Strongman Helen , Carreira Helena , De Stavola Bianca L , Bhaskaran Krishnan , Leon David A 
Published: June 2021

AbstractObjectivesExcess mortality captures the total effect of the COVID-19 pandemic on mortality and is not affected by mis-specification of cause of death. We aimed to describe how health and demographic factors have been associated with excess mortality during the pandemic.DesignTime-series analysis.SettingUK primary care data from practices contributing to the Clinical Practice Research Datalink on July 31st 2020.ParticipantsWe constructed a time-series dataset including 9,635,613 adults (≥40 years old) who were actively registered at the general practice during the study period.Main outcome measuresWe extracted weekly numbers of deaths between March 2015 and July 2020, stratified by individual-level factors. Excess mortality during wave 1 of the UK pandemic (5th March to 27th May 2020) compared to pre-pandemic was estimated using seasonally adjusted negative binomial regression models. Relative rates of death for a range of factors were estimated before and during wave 1 by including interaction terms.ResultsAll-cause mortality increased by 43% (95% CI 40%-47%) during wave 1 compared with pre-pandemic. Changes to the relative rate of death associated with most socio-demographic and clinical characteristics were small during wave 1 compared with pre-pandemic. However, the mortality rate associated with dementia markedly increased (RR for dementia vs no dementia pre-pandemic: 3.5, 95% CI 3.4-3.5; RR during wave 1: 5.1, 4.87-5.28); a similar pattern was seen for learning disabilities (RR pre-pandemic: 3.6, 3.4-3.5; during wave 1: 4.8, 4.4-5.3), for Black or South Asian ethnicity compared to white, and for London compared to other regions.ConclusionsThe first UK COVID-19 wave appeared to amplify baseline mortality risk by a relatively constant factor for most population subgroups. However disproportionate increases in mortality were seen for those with dementia, learning disabilities, non-white ethnicity, or living in London.Summary boxWhat is already known on this topicAll-cause mortality during the COVID-19 pandemic was higher than in previous years; this excess mortality was particularly pronounced among elderly people, males, people of non-white ethnicity, people of lower socio-economic status and people living in care-homes.Several other papers have studied a wider range of factors associated with mortality due to COVID-19 using cause-of-death data.There is little evidence on how all-cause mortality has changed in people with comorbidities.What this study addsOur study shows that during Wave 1 of the pandemic all cause death rates increased by a similar proportional degree for almost all population subgroups regardless of their health or socio-demographic circumstances; the exceptions were those with a diagnosis of dementia or learning disabilities and those of non-white ethnicity or living in London.This suggests that COVID-19 has dialled up the risk of death by a similar proportional degree for everyone except those exposed to a higher risk of infection.