Time-sensitive testing pressures and COVID-19 outcomes: are socioeconomic inequalities over the first year of the pandemic explained by selection bias?

Alice R Carter; Gemma L Clayton; M Carolina Borges; Laura D Howe; Rachael A Hughes; George Davey Smith; Deborah A Lawlor; Kate Tilling; Gareth J Griffith

doi:10.1186/s12889-023-16767-5

Time-sensitive testing pressures and COVID-19 outcomes: are socioeconomic inequalities over the first year of the pandemic explained by selection bias?

Alice R Carter, Gemma L Clayton, M Carolina Borges, Laura D Howe, Rachael A Hughes, George Davey Smith, Deborah A Lawlor, Kate Tilling, Gareth J Griffith^*

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

Abstract

BACKGROUND: There are many ways in which selection bias might impact COVID-19 research. Here we focus on selection for receiving a polymerase-chain-reaction (PCR) SARS-CoV-2 test and how known changes to selection pressures over time may bias research into COVID-19 infection.

METHODS: Using UK Biobank (N = 420,231; 55% female; mean age = 66.8 [SD = 8·11]) we estimate the association between socio-economic position (SEP) and (i) being tested for SARS-CoV-2 infection versus not being tested (ii) testing positive for SARS-CoV-2 infection versus testing negative and (iii) testing negative for SARS-CoV-2 infection versus not being tested. We construct four distinct time-periods between March 2020 and March 2021, representing distinct periods of testing pressures and lockdown restrictions and specify both time-stratified and combined models for each outcome. We explore potential selection bias by examining associations with positive and negative control exposures.

RESULTS: The association between more disadvantaged SEP and receiving a SARS-CoV-2 test attenuated over time. Compared to individuals with a degree, individuals whose highest educational qualification was a GCSE or equivalent had an OR of 1·27 (95% CI: 1·18 to 1·37) in March-May 2020 and 1·13 (95% CI: 1.·10 to 1·16) in January-March 2021. The magnitude of the association between educational attainment and testing positive for SARS-CoV-2 infection increased over the same period. For the equivalent comparison, the OR for testing positive increased from 1·25 (95% CI: 1·04 to 1·47), to 1·69 (95% CI: 1·55 to 1·83). We found little evidence of an association between control exposures, and any considered outcome.

CONCLUSIONS: The association between SEP and SARS-CoV-2 testing changed over time, highlighting the potential of time-specific selection pressures to bias analyses of COVID-19. Positive and negative control analyses suggest that changes in the association between SEP and SARS-CoV-2 infection over time likely reflect true increases in socioeconomic inequalities.

Original language	English
Article number	1863
Journal	BMC Public Health
Volume	23
Issue number	1
DOIs	https://doi.org/10.1186/s12889-023-16767-5
Publication status	Published - 26 Sept 2023

Bibliographical note

Funding Information:
KT has acted as a consultant for CHDI foundation. DAL acknowledges support from Roche Diagnostics and Medtronic Ltd for research unrelated to that presented here. All other authors declare they have no conflict of interest, financial or otherwise.

Funding Information:
This work was supported by the University of Bristol and Medical Research Council (MRC) Integrative Epidemiology Unit (MC_UU_00032/01, MC_UU_00032/02, MC_UU_00032/05), supporting all authors; the Bristol British Heart Foundation Accelerator Award (AA/18/1/34219), which supports ARC, MCB and DAL; the European Union’s Horizon 2020 research and innovation programme under grant agreement No 733206 (LifeCycle), which supports GLC and DAL; a University of Bristol Vice-Chancellor’s Fellowship which supports MCB; an MRC Career Development Award (MR/M020894/1), which supports LDH; a Wellcome Trust and Royal Society Sir Henry Dale Fellowship (Grant Number 215408/Z/19/Z) which supports RAH; a British Heart Foundation Chair (CH/F/20/90003) and a National Institute of Health Research Senior Investigator award (NF-0616-10102) which both support DAL; the Economic and Social Research Council (ES/T009101/1), postdoctoral fellowship which supports GJG. This work was conducted as part of the National Institute of Health Research (NIHR) and British Heart Foundation (BHF) COVID Flagship project (COVIDITY). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ARC and GJG serve as the guarantors.

Publisher Copyright:
© 2023, BioMed Central Ltd., part of Springer Nature.

Research Groups and Themes

Bristol Population Health Science Institute

Keywords

Female
Humans
Aged
Male
Selection Bias
COVID-19/diagnosis
Pandemics
COVID-19 Testing
SARS-CoV-2
Communicable Disease Control
Educational Status

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

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IEU: MRC Integrative Epidemiology Unit Quinquennial renewal
Gaunt, L. F. (Principal Investigator) & Davey Smith, G. (Principal Investigator)
1/04/18 → 31/03/23
Project: Research

Cite this

Carter, A. R., Clayton, G. L., Borges, M. C., Howe, L. D., Hughes, R. A., Smith, G. D., Lawlor, D. A., Tilling, K., & Griffith, G. J. (2023). Time-sensitive testing pressures and COVID-19 outcomes: are socioeconomic inequalities over the first year of the pandemic explained by selection bias? BMC Public Health, 23(1), Article 1863. https://doi.org/10.1186/s12889-023-16767-5

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title = "Time-sensitive testing pressures and COVID-19 outcomes: are socioeconomic inequalities over the first year of the pandemic explained by selection bias?",

abstract = "BACKGROUND: There are many ways in which selection bias might impact COVID-19 research. Here we focus on selection for receiving a polymerase-chain-reaction (PCR) SARS-CoV-2 test and how known changes to selection pressures over time may bias research into COVID-19 infection.METHODS: Using UK Biobank (N = 420,231; 55% female; mean age = 66.8 [SD = 8·11]) we estimate the association between socio-economic position (SEP) and (i) being tested for SARS-CoV-2 infection versus not being tested (ii) testing positive for SARS-CoV-2 infection versus testing negative and (iii) testing negative for SARS-CoV-2 infection versus not being tested. We construct four distinct time-periods between March 2020 and March 2021, representing distinct periods of testing pressures and lockdown restrictions and specify both time-stratified and combined models for each outcome. We explore potential selection bias by examining associations with positive and negative control exposures.RESULTS: The association between more disadvantaged SEP and receiving a SARS-CoV-2 test attenuated over time. Compared to individuals with a degree, individuals whose highest educational qualification was a GCSE or equivalent had an OR of 1·27 (95% CI: 1·18 to 1·37) in March-May 2020 and 1·13 (95% CI: 1.·10 to 1·16) in January-March 2021. The magnitude of the association between educational attainment and testing positive for SARS-CoV-2 infection increased over the same period. For the equivalent comparison, the OR for testing positive increased from 1·25 (95% CI: 1·04 to 1·47), to 1·69 (95% CI: 1·55 to 1·83). We found little evidence of an association between control exposures, and any considered outcome.CONCLUSIONS: The association between SEP and SARS-CoV-2 testing changed over time, highlighting the potential of time-specific selection pressures to bias analyses of COVID-19. Positive and negative control analyses suggest that changes in the association between SEP and SARS-CoV-2 infection over time likely reflect true increases in socioeconomic inequalities.",

keywords = "Female, Humans, Aged, Male, Selection Bias, COVID-19/diagnosis, Pandemics, COVID-19 Testing, SARS-CoV-2, Communicable Disease Control, Educational Status",

author = "Carter, {Alice R} and Clayton, {Gemma L} and Borges, {M Carolina} and Howe, {Laura D} and Hughes, {Rachael A} and Smith, {George Davey} and Lawlor, {Deborah A} and Kate Tilling and Griffith, {Gareth J}",

note = "Funding Information: KT has acted as a consultant for CHDI foundation. DAL acknowledges support from Roche Diagnostics and Medtronic Ltd for research unrelated to that presented here. All other authors declare they have no conflict of interest, financial or otherwise. Funding Information: This work was supported by the University of Bristol and Medical Research Council (MRC) Integrative Epidemiology Unit (MC_UU_00032/01, MC_UU_00032/02, MC_UU_00032/05), supporting all authors; the Bristol British Heart Foundation Accelerator Award (AA/18/1/34219), which supports ARC, MCB and DAL; the European Union{\textquoteright}s Horizon 2020 research and innovation programme under grant agreement No 733206 (LifeCycle), which supports GLC and DAL; a University of Bristol Vice-Chancellor{\textquoteright}s Fellowship which supports MCB; an MRC Career Development Award (MR/M020894/1), which supports LDH; a Wellcome Trust and Royal Society Sir Henry Dale Fellowship (Grant Number 215408/Z/19/Z) which supports RAH; a British Heart Foundation Chair (CH/F/20/90003) and a National Institute of Health Research Senior Investigator award (NF-0616-10102) which both support DAL; the Economic and Social Research Council (ES/T009101/1), postdoctoral fellowship which supports GJG. This work was conducted as part of the National Institute of Health Research (NIHR) and British Heart Foundation (BHF) COVID Flagship project (COVIDITY). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ARC and GJG serve as the guarantors. Publisher Copyright: {\textcopyright} 2023, BioMed Central Ltd., part of Springer Nature.",

year = "2023",

month = sep,

day = "26",

doi = "10.1186/s12889-023-16767-5",

language = "English",

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journal = "BMC Public Health",

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TY - JOUR

T1 - Time-sensitive testing pressures and COVID-19 outcomes

T2 - are socioeconomic inequalities over the first year of the pandemic explained by selection bias?

AU - Carter, Alice R

AU - Clayton, Gemma L

AU - Borges, M Carolina

AU - Howe, Laura D

AU - Hughes, Rachael A

AU - Smith, George Davey

AU - Lawlor, Deborah A

AU - Tilling, Kate

AU - Griffith, Gareth J

N1 - Funding Information: KT has acted as a consultant for CHDI foundation. DAL acknowledges support from Roche Diagnostics and Medtronic Ltd for research unrelated to that presented here. All other authors declare they have no conflict of interest, financial or otherwise. Funding Information: This work was supported by the University of Bristol and Medical Research Council (MRC) Integrative Epidemiology Unit (MC_UU_00032/01, MC_UU_00032/02, MC_UU_00032/05), supporting all authors; the Bristol British Heart Foundation Accelerator Award (AA/18/1/34219), which supports ARC, MCB and DAL; the European Union’s Horizon 2020 research and innovation programme under grant agreement No 733206 (LifeCycle), which supports GLC and DAL; a University of Bristol Vice-Chancellor’s Fellowship which supports MCB; an MRC Career Development Award (MR/M020894/1), which supports LDH; a Wellcome Trust and Royal Society Sir Henry Dale Fellowship (Grant Number 215408/Z/19/Z) which supports RAH; a British Heart Foundation Chair (CH/F/20/90003) and a National Institute of Health Research Senior Investigator award (NF-0616-10102) which both support DAL; the Economic and Social Research Council (ES/T009101/1), postdoctoral fellowship which supports GJG. This work was conducted as part of the National Institute of Health Research (NIHR) and British Heart Foundation (BHF) COVID Flagship project (COVIDITY). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ARC and GJG serve as the guarantors. Publisher Copyright: © 2023, BioMed Central Ltd., part of Springer Nature.

PY - 2023/9/26

Y1 - 2023/9/26

N2 - BACKGROUND: There are many ways in which selection bias might impact COVID-19 research. Here we focus on selection for receiving a polymerase-chain-reaction (PCR) SARS-CoV-2 test and how known changes to selection pressures over time may bias research into COVID-19 infection.METHODS: Using UK Biobank (N = 420,231; 55% female; mean age = 66.8 [SD = 8·11]) we estimate the association between socio-economic position (SEP) and (i) being tested for SARS-CoV-2 infection versus not being tested (ii) testing positive for SARS-CoV-2 infection versus testing negative and (iii) testing negative for SARS-CoV-2 infection versus not being tested. We construct four distinct time-periods between March 2020 and March 2021, representing distinct periods of testing pressures and lockdown restrictions and specify both time-stratified and combined models for each outcome. We explore potential selection bias by examining associations with positive and negative control exposures.RESULTS: The association between more disadvantaged SEP and receiving a SARS-CoV-2 test attenuated over time. Compared to individuals with a degree, individuals whose highest educational qualification was a GCSE or equivalent had an OR of 1·27 (95% CI: 1·18 to 1·37) in March-May 2020 and 1·13 (95% CI: 1.·10 to 1·16) in January-March 2021. The magnitude of the association between educational attainment and testing positive for SARS-CoV-2 infection increased over the same period. For the equivalent comparison, the OR for testing positive increased from 1·25 (95% CI: 1·04 to 1·47), to 1·69 (95% CI: 1·55 to 1·83). We found little evidence of an association between control exposures, and any considered outcome.CONCLUSIONS: The association between SEP and SARS-CoV-2 testing changed over time, highlighting the potential of time-specific selection pressures to bias analyses of COVID-19. Positive and negative control analyses suggest that changes in the association between SEP and SARS-CoV-2 infection over time likely reflect true increases in socioeconomic inequalities.

AB - BACKGROUND: There are many ways in which selection bias might impact COVID-19 research. Here we focus on selection for receiving a polymerase-chain-reaction (PCR) SARS-CoV-2 test and how known changes to selection pressures over time may bias research into COVID-19 infection.METHODS: Using UK Biobank (N = 420,231; 55% female; mean age = 66.8 [SD = 8·11]) we estimate the association between socio-economic position (SEP) and (i) being tested for SARS-CoV-2 infection versus not being tested (ii) testing positive for SARS-CoV-2 infection versus testing negative and (iii) testing negative for SARS-CoV-2 infection versus not being tested. We construct four distinct time-periods between March 2020 and March 2021, representing distinct periods of testing pressures and lockdown restrictions and specify both time-stratified and combined models for each outcome. We explore potential selection bias by examining associations with positive and negative control exposures.RESULTS: The association between more disadvantaged SEP and receiving a SARS-CoV-2 test attenuated over time. Compared to individuals with a degree, individuals whose highest educational qualification was a GCSE or equivalent had an OR of 1·27 (95% CI: 1·18 to 1·37) in March-May 2020 and 1·13 (95% CI: 1.·10 to 1·16) in January-March 2021. The magnitude of the association between educational attainment and testing positive for SARS-CoV-2 infection increased over the same period. For the equivalent comparison, the OR for testing positive increased from 1·25 (95% CI: 1·04 to 1·47), to 1·69 (95% CI: 1·55 to 1·83). We found little evidence of an association between control exposures, and any considered outcome.CONCLUSIONS: The association between SEP and SARS-CoV-2 testing changed over time, highlighting the potential of time-specific selection pressures to bias analyses of COVID-19. Positive and negative control analyses suggest that changes in the association between SEP and SARS-CoV-2 infection over time likely reflect true increases in socioeconomic inequalities.

KW - Female

KW - Humans

KW - Aged

KW - Male

KW - Selection Bias

KW - COVID-19/diagnosis

KW - Pandemics

KW - COVID-19 Testing

KW - SARS-CoV-2

KW - Communicable Disease Control

KW - Educational Status

U2 - 10.1186/s12889-023-16767-5

DO - 10.1186/s12889-023-16767-5

M3 - Article (Academic Journal)

C2 - 37752486

SN - 1471-2458

VL - 23

JO - BMC Public Health

JF - BMC Public Health

IS - 1

M1 - 1863

ER -

Time-sensitive testing pressures and COVID-19 outcomes: are socioeconomic inequalities over the first year of the pandemic explained by selection bias?

Abstract

Bibliographical note

Research Groups and Themes

Keywords

UN SDGs

Access to Document

Handle.net

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Projects

IEU: MRC Integrative Epidemiology Unit Quinquennial renewal

Cite this