| Title: | Time-sensitive testing pressures and COVID-19 outcomes: are socioeconomic inequalities over the first year of the pandemic explained by selection bias? |
| Journal: | BMC Public Health |
| Published: | 26 Sep 2023 |
| Pubmed: | https://pubmed.ncbi.nlm.nih.gov/37752486/ |
| DOI: | https://doi.org/10.1186/s12889-023-16767-5 |
| URL: | https://bmcpublichealth.biomedcentral.com/counter/pdf/10.1186/s12889-023-16767-5 |
Publication 9469
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Abstract
BackgroundThere 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.MethodsUsing 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.ResultsThe 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.ConclusionsThe 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.</p>
9 Authors
- 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
1 Application
| Application ID | Title |
|---|---|
| 16729 | MR-PheWAS: hypothesis prioritization among potential causal effects of body mass index on many outcomes with Mendelian randomisation, using 500K participants of the UK biobank |
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