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The Impact of Primary Care Supported Shielding on the Risk of Mortality in People Vulnerable to COVID-19: English Sentinel Network Matched Cohort Study

23 Pages Posted: 28 Oct 2020

See all articles by Azmaeen Zarif

Azmaeen Zarif

Nuffield Department of Primary Care Health Sciences, University of Oxford

Mark Joy

University of Oxford - Nuffield Department of Primary Care Health Sciences

Julian Sherlock

University of Oxford - Nuffield Department of Primary Care Health Sciences

James Sheppard

Nuffield Department of Primary Care Health Sciences, University of Oxford

Rachel Byford

University of Oxford - Nuffield Department of Primary Care Health Sciences

Oluwafunmi Akinyemi

University of Oxford - Nuffield Department of Primary Care Health Sciences

Clare Bankhead

University of Oxford - Nuffield Department of Primary Care Health Sciences

Alexandra Deeks

University of Oxford - Peter Medawar Building for Pathogen Research

Filipa Ferreira

University of Oxford - Nuffield Department of Primary Care Health Sciences

Nicholas Jones

Nuffield Department of Primary Care Health Sciences, University of Oxford

Harshana Liyanage

Nuffield Department of Primary Care Health Sciences, University of Oxford

Dylan McGagh

Nuffield Department of Primary Care Health Sciences, University of Oxford

Brian D. Nicholson

University of Oxford - Nuffield Department of Primary Care Health Sciences

Jason Oke

University of Oxford

Cecilia Okusi

University of Oxford - Nuffield Department of Primary Care Health Sciences

Manasa Tripathy

University of Oxford - Nuffield Department of Primary Care Health Sciences

John Williams

University of Oxford - Nuffield Department of Primary Care Health Sciences

Richard Hobbs

University of Oxford - Nuffield Department of Primary Care Health Sciences

Simon de Lusignan

University of Oxford; Royal College of General Practitioners - Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC); University of Surrey - Department of Clinical & Experimental Medicine

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Abstract

Background: There was excess mortality from the first wave of coronavirus 2019 infection (COVID-19), which mainly affected older people. To mitigate risk, the UK government recommended ‘shielding’ of vulnerable people through self-isolation for 12 weeks. We investigated the impact of primary care-reinforced shielding advice on all-cause mortality.

Methods: We conducted a retrospective cohort study using a nationally representative English primary care database. We compare people aged >=40years who were recorded as being advised to shield using a fixed ratio of 1:1, matching (a mixture of exact and propensity score matching) to people with the same diagnoses not advised to shield (n=77,360 per group). Time-to-death was compared using Cox regression, reporting the hazard ratio (HR) of mortality between groups. A sensitivity analysis compared exact matched cohorts (n=24,752 shielded, n=61,566 exact matches).  

Findings: Over the follow-up period, we found a time-varying HR of mortality between groups. In the first 21 days, the mortality risk in people shielding was half those not (HR=0.50, 95%CI:0.41-0.59. p<0.0001). Over the remaining nine weeks, mortality risk was 54% higher in the shielded group (HR=1.54, 95%CI:1.41-1.70, p<0.0001). Beyond the shielding period, mortality risk was over two-and-a-half times higher in the shielded group (HR=2.61, 95%CI:2.38-2.87, p<0.0001).

Interpretation: General practitioner-reinforced advice to shield halved the risk of mortality for 21 days compared to those who were not. Mortality risk became higher across the remainder of the shielding period, rising to two-and-a-half times greater post-shielding. Shielding may be beneficial in the next wave of COVID-19.

Funding Statement: NIHR School of Primary Care, Public Health England

Declaration of Interests: SdeL is the director of RCGP RSC. He has unrelated projects funded by GSK, Seqirus and has been a member of Global Advisory Boards for Seqirus and Sanofi. FDRH reports personal fees from Novartis and Boehringer Ingelheim and grants from Pfizer. All other authors declare no competing interests.

Ethics Approval Statement: The RCGP RSC’s work concerning SARS-CoV-2 has been approved by Public Health England’s Caldicott Guardian Committee as fitting under Regulation 3 of the Health Service Control Patient Information Regulations 2002. The study was approved by RCGP.

Keywords: Shielding, COVID-19, mortality risk, hazard ratio, matched, clinically vulnerable, GP

Suggested Citation

Zarif, Azmaeen and Joy, Mark and Sherlock, Julian and Sheppard, James and Byford, Rachel and Akinyemi, Oluwafunmi and Bankhead, Clare and Deeks, Alexandra and Ferreira, Filipa and Jones, Nicholas and Liyanage, Harshana and McGagh, Dylan and Nicholson, Brian D. and Oke, Jason and Okusi, Cecilia and Tripathy, Manasa and Williams, John and Hobbs, F.D. Richard and de Lusignan, Simon, The Impact of Primary Care Supported Shielding on the Risk of Mortality in People Vulnerable to COVID-19: English Sentinel Network Matched Cohort Study. Available at SSRN: https://ssrn.com/abstract=3719054 or http://dx.doi.org/10.2139/ssrn.3719054

Azmaeen Zarif

Nuffield Department of Primary Care Health Sciences, University of Oxford ( email )

Mark Joy

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

Julian Sherlock

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

James Sheppard

Nuffield Department of Primary Care Health Sciences, University of Oxford ( email )

Rachel Byford

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

Oluwafunmi Akinyemi

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

Clare Bankhead

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Alexandra Deeks

University of Oxford - Peter Medawar Building for Pathogen Research

South Parks Road
OX2 3SY
United Kingdom

Filipa Ferreira

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

Nicholas Jones

Nuffield Department of Primary Care Health Sciences, University of Oxford ( email )

Harshana Liyanage

Nuffield Department of Primary Care Health Sciences, University of Oxford ( email )

Dylan McGagh

Nuffield Department of Primary Care Health Sciences, University of Oxford ( email )

Brian D. Nicholson

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Jason Oke

University of Oxford ( email )

Cecilia Okusi

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

Manasa Tripathy

University of Oxford - Nuffield Department of Primary Care Health Sciences

Oxford
United Kingdom

John Williams

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

F.D. Richard Hobbs

University of Oxford - Nuffield Department of Primary Care Health Sciences ( email )

Oxford
United Kingdom

Simon De Lusignan (Contact Author)

University of Oxford ( email )

Eagle House,
Walton Well Road,
Oxford, OX2 6ED
United Kingdom

HOME PAGE: http://https://orchid.phc.ox.ac.uk

Royal College of General Practitioners - Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) ( email )

30 Euston Square
London
United Kingdom

University of Surrey - Department of Clinical & Experimental Medicine ( email )

Guildford
United Kingdom