The impact of primary care supported shielding on the risk of mortality in people vulnerable to COVID-19: English sentinel network matched cohort study

Azmaeen Zarif; Mark Joy; Julian Sherlock; James P Sheppard; Rachel Byford; Oluwafunmi Akinyemi; Clare R Bankhead; Alexandra Deeks; Filipa Ferreira; Nicholas Jones; Harshana Liyanage; Dylan McGagh; Brian Nicholson; Jason Oke; Cecilia Okusi; Manasa Tripathy; John Williams; Richard Hobbs; Simon de Lusignan

doi:10.1016/j.jinf.2021.04.033

The impact of primary care supported shielding on the risk of mortality in people vulnerable to COVID-19: English sentinel network matched cohort study

J Infect. 2021 Aug;83(2):228-236. doi: 10.1016/j.jinf.2021.04.033. Epub 2021 May 15.

Authors

Azmaeen Zarif¹, Mark Joy², Julian Sherlock³, James P Sheppard⁴, Rachel Byford⁵, Oluwafunmi Akinyemi⁶, Clare R Bankhead⁷, Alexandra Deeks⁸, Filipa Ferreira⁹, Nicholas Jones¹⁰, Harshana Liyanage¹¹, Dylan McGagh¹², Brian Nicholson¹³, Jason Oke¹⁴, Cecilia Okusi¹⁵, Manasa Tripathy¹⁶, John Williams¹⁷, Richard Hobbs¹⁸, Simon de Lusignan¹⁹

Affiliations

¹ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
² Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
³ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
⁴ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
⁵ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
⁶ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
⁷ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
⁸ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
⁹ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹⁰ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹¹ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹² Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹³ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹⁴ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹⁵ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹⁶ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹⁷ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹⁸ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK. Electronic address: [email protected].
¹⁹ Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford OX2 6GG, UK; Royal College of General Practitioners, Euston Square, London NW1 2FB, UK. Electronic address: [email protected].

Abstract

Objectives: To mitigate risk of mortality from coronavirus 2019 infection (COVID-19), the UK government recommended 'shielding' of vulnerable people through self-isolation for 12 weeks.

Methods: A retrospective cohort study using a nationally representative English primary care database comparing people aged >= 40 years who were recorded as being advised to shield using a fixed ratio of 1:1, 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).

Results: 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).

Conclusions: Shielding halved the risk of mortality for 21 days. 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.

Keywords: COVID-19; Medical records system; Mortality; Shielding; computerized.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

COVID-19*
Cohort Studies
Humans
Primary Health Care
Retrospective Studies
SARS-CoV-2

Grants and funding

WT_/Wellcome Trust/United Kingdom