Effects of increased body mass index on employment status: a Mendelian randomisation study

Campbell, D. D. et al. (2021) Effects of increased body mass index on employment status: a Mendelian randomisation study. International Journal of Obesity, 45(8), pp. 1790-1801. (doi: 10.1038/s41366-021-00846-x) (PMID:34158612)

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Background: The obesity epidemic may have substantial implications for the global workforce, including causal effects on employment, but clear evidence is lacking. Obesity may prevent people from being in paid work through poor health or through social discrimination. We studied genetic variants robustly associated with body mass index (BMI) to investigate its causal effects on employment. Dataset/methods: White UK ethnicity participants of working age (men 40–64 years, women 40–59 years), with suitable genetic data were selected in the UK Biobank study (N = 230,791). Employment status was categorised in two ways: first, contrasting being in paid employment with any other status; and second, contrasting being in paid employment with sickness/disability, unemployment, early retirement and caring for home/family. Socioeconomic indicators also investigated were hours worked, household income, educational attainment and Townsend deprivation index (TDI). We conducted observational and two-sample Mendelian randomisation (MR) analyses to investigate the effect of increased BMI on employment-related outcomes. Results: Regressions showed BMI associated with all the employment-related outcomes investigated. MR analyses provided evidence for higher BMI causing increased risk of sickness/disability (OR 1.08, 95% CI 1.04, 1.11, per 1 Kg/m2 BMI increase) and decreased caring for home/family (OR 0.96, 95% CI 0.93, 0.99), higher TDI (Beta 0.038, 95% CI 0.018, 0.059), and lower household income (OR 0.98, 95% CI 0.96, 0.99). In contrast, MR provided evidence for no causal effect of BMI on unemployment, early retirement, non-employment, hours worked or educational attainment. There was little evidence for causal effects differing by sex or age. Robustness tests yielded consistent results. Discussion: BMI appears to exert a causal effect on employment status, largely by affecting an individual’s health rather than through increased unemployment arising from social discrimination. The obesity epidemic may be contributing to increased worklessness and therefore could impose a substantial societal burden.

Item Type:Articles
Additional Information:This research was supported by The Health Foundation, Social and economic value of health award (756273), Medical Research Council grant (MC_UU_12017/13), and Chief Scientist Office Grant (SPHSU13). This research has been conducted using the UK Biobank Resource under Application Number 17333. We thank all participants, staff and funders of the UK Biobank study, and the NHS staff who collected data provided by patients as part of their care and support. ED acknowledges funding by MRC Strategic Award (MC_PC_13027). JW is supported by a Lister Prize Fellowship (173096). KJ is supported by an MRC Doctoral Training Programme Studentship at the Universities of Glasgow and Edinburgh. DS acknowledges the support of the Brain and Behaviour Research Foundation (Independent Investigator Award 1930) and a Lister Prize Fellowship (173096). RS is supported by a UKRI Innovation-HDR-UK Fellowship (MR/S003061/1). DC is supported by a Health Foundation, Social and economic value of health award (756273). MG acknowledges funding from the Medical Research Council (MC_UU_12017/13) and Chief Scientist Office Grant (SPHSU13), as well as under the Health Foundation grant (756273). SVK acknowledges funding from a NRS Senior Clinical Fellowship (SCAF/15/02), the Medical Research Council (MC_UU_12017/13 & MC_UU_12017/15), the Scottish Government Chief Scientist Office (SPHSU13) and the Health Foundation (756273).
Glasgow Author(s) Enlighten ID:Katikireddi, Professor Vittal and Popham, Dr Frank and Ward, Dr Joey and Johnston, Ms Keira and Demou, Dr Evangelia and Green, Dr Michael and Smith, Professor Daniel and Campbell, Dr Desmond and Strawbridge, Dr Rona
Authors: Campbell, D. D., Green, M., Davies, N., Demou, E., Ward, J., Howe, L. D., Harrison, S., Johnston, K. J.A., Strawbridge, R., Popham, F., Smith, D. J., Munafò, M. R., and Katikireddi, S. V.
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Mental Health and Wellbeing
College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > MRC/CSO SPHSU
Journal Name:International Journal of Obesity
Publisher:Nature Research
ISSN (Online):1476-5497
Published Online:22 June 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in International Journal of Obesity 45(8): 1790-1801
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
3048230021Inequalities in healthAlastair LeylandMedical Research Council (MRC)MC_UU_00022/2HW - MRC/CSO Social and Public Health Sciences Unit
727651Measuring and Analysing Socioeconomic Inequalities in HealthAlastair LeylandOffice of the Chief Scientific Adviser (CSO)SPHSU13HW - MRC/CSO Social and Public Health Sciences Unit
302131Understanding the excess risk of cardiometabolic disease in individuals with serious mental illnessJill PellMedical Research Council (MRC)MR/S003061/1SHW - Public Health
168560MRC SPHSU/GU Transfer FellowshipsLaurence MooreMedical Research Council (MRC)MC_PC_13027SHW - MRC/CSO Social & Public Health Sciences Unit