Long working hours, socioeconomic status, and the risk of incident type 2 diabetes: a meta-analysis of published and unpublished data from 222 120 individuals
Year: 2014
Type: review
Study designs: Systematic Review, Meta-Analysis
Abstract: BACKGROUND: Working long hours might have adverse health effects, but whether this is true for all socioeconomic status groups is unclear. In this meta-analysis stratified by socioeconomic status, we investigated the role of long working hours as a risk factor for type 2 diabetes. METHODS: We identified four published studies through a systematic literature search of PubMed and Embase up to April 30, 2014. Study inclusion criteria were English-language publication; prospective design (cohort study); investigation of the effect of working hours or overtime work; incident diabetes as an outcome; and relative risks, odds ratios, or hazard ratios (HRs) with 95% CIs, or sufficient information to calculate these estimates. Additionally, we used unpublished individual-level data from 19 cohort studies from the Individual-Participant-Data Meta-analysis in Working-Populations Consortium and international open-access data archives. Effect estimates from published and unpublished data from 222 120 men and women from the USA, Europe, Japan, and Australia were pooled with random-effects meta-analysis. FINDINGS: During 1·7 million person-years at risk, 4963 individuals developed diabetes (incidence 29 per 10 000 person-years). The minimally adjusted summary risk ratio for long (≥55 h per week) compared with standard working hours (35-40 h) was 1·07 (95% CI 0·89-1·27, difference in incidence three cases per 10 000 person-years) with significant heterogeneity in study-specific estimates (I(2)=53%, p=0·0016). In an analysis stratified by socioeconomic status, the association between long working hours and diabetes was evident in the low socioeconomic status group (risk ratio 1·29, 95% CI 1·06-1·57, difference in incidence 13 per 10 000 person-years, I(2)=0%, p=0·4662), but was null in the high socioeconomic status group (1·00, 95% CI 0·80-1·25, incidence difference zero per 10 000 person-years, I(2)=15%, p=0·2464). The association in the low socioeconomic status group was robust to adjustment for age, sex, obesity, and physical activity, and remained after exclusion of shift workers. INTERPRETATION: In this meta-analysis, the link between longer working hours and type 2 diabetes was apparent only in individuals in the low socioeconomic status groups. FUNDING: Medical Research Council, European Union New and Emerging Risks in Occupational Safety and Health research programme, Finnish Work Environment Fund, Swedish Research Council for Working Life and Social Research, German Social Accident Insurance, Danish National Research Centre for the Working Environment, Academy of Finland, Ministry of Social Affairs and Employment (Netherlands), Economic and Social Research Council, US National Institutes of Health, and British Heart Foundation.
Authors: Mika Kivimäki, Marianna Virtanen, Ichiro Kawachi, Solja T Nyberg, Lars Alfredsson, G David Batty, Jakob B Bjorner, Marianne Borritz, Eric J Brunner, Hermann Burr, Nico Dragano, Jane E Ferrie, Eleonor I Fransson, Mark Hamer, Katriina Heikkilä, Anders Knutsson, Markku Koskenvuo, Ida E H Madsen, Martin L Nielsen, Maria Nordin, Tuula Oksanen, Jan H Pejtersen, Jaana Pentti, Reiner Rugulies, Paula Salo, Johannes Siegrist, Andrew Steptoe, Sakari Suominen, Töres Theorell, Jussi Vahtera, Peter J M Westerholm, Hugo Westerlund, Archana Singh-Manoux, Markus Jokela
Institutions: University of Helsinki, University College London, Finnish Institute of Occupational Health, Harvard University, Region Stockholm, Karolinska Institutet, Alzheimer Scotland, University of Edinburgh, National Research Centre for the Working Environment, Bispebjerg Hospital, Copenhagen University Hospital, Federal Institute for Occupational Safety and Health, Heinrich Heine University Düsseldorf, University of Bristol, Stockholm University, Jönköping University, University of Tampere, Mid Sweden University, Umeå University, Danish National Centre for Social Research, University of Copenhagen, University of Turku, Nordic School of Public Health, Folkhälsans Forskningscentrum, Turku University Hospital, Uppsala University, Inserm, Centre de recherche en Epidémiologie et Santé des Populations
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $7,280
Funders: National Research Centre, Ministerie van Sociale Zaken en Werkgelegenheid, British Heart Foundation, European Commission, Työsuojelurahasto, Deutsche Gesetzliche Unfallversicherung, Vetenskapsrådet, NordForsk, National Institutes of Health, Medical Research Council, Economic and Social Research Council, National Institute on Aging, National Heart, Lung, and Blood Institute
Awards: Centre for Cognitive Ageing & Cognitive Epidemiology, G1492072473, G2294100661, G2425175678, Health behaviors over the adult lifecourse and cognitive aging, Determinants of healthy ageing in the Whitehall II study, G3099752742, G400652325, Psychosocial work environment and healthy ageing, G6078043905, G6122601559, Adult Determinants of Late Life Depression, Cognitive Decline and Physical Functioning - The Whitehall II Ageing Study, Vascular risk and functional decline in old age (renewal), G7732418067, Integrative Pathways to Health and Illness, Socioeconomic gradient in CHD in early old age
OpenAlex ID: W2148375661