TY - JOUR
T1 - Long working hours and risk of coronary heart disease and stroke
T2 - a systematic review and meta-analysis of published and unpublished data for 603,838 individuals
AU - Kivimäki, Mika
AU - Jokela, Markus
AU - Nyberg, Solja T
AU - Singh-Manoux, Archana
AU - Fransson, Eleonor I
AU - Alfredsson, Lars
AU - Bjorner, Jakob B
AU - Borritz, Marianne
AU - Burr, Hermann
AU - Casini, Annalisa
AU - Clays, Els
AU - De Bacquer, Dirk
AU - Dragano, Nico
AU - Erbel, Raimund
AU - Geuskens, Goedele A
AU - Hamer, Mark
AU - Hooftman, Wendela E
AU - Houtman, Irene L
AU - Jöckel, Karl-Heinz
AU - Kittel, France
AU - Knutsson, Anders
AU - Koskenvuo, Markku
AU - Lunau, Thorsten
AU - Madsen, Ida E H
AU - Nielsen, Martin L
AU - Nordin, Maria
AU - Oksanen, Tuula
AU - Pejtersen, Jan H
AU - Pentti, Jaana
AU - Rugulies, Reiner
AU - Salo, Paula
AU - Shipley, Martin J
AU - Siegrist, Johannes
AU - Steptoe, Andrew
AU - Suominen, Sakari B
AU - Theorell, Töres
AU - Vahtera, Jussi
AU - Westerholm, Peter J M
AU - Westerlund, Hugo
AU - O'Reilly, Dermot
AU - Kumari, Meena
AU - Batty, G David
AU - Ferrie, Jane E
AU - Virtanen, Marianna
AU - IPD-Work Consortium
N1 - Copyright © 2015 Kivimäki et al. Open Access article distributed under the terms of CC BY. Published by Elsevier Ltd.. All rights reserved.
PY - 2015/10/31
Y1 - 2015/10/31
N2 - BACKGROUND: Long working hours might increase the risk of cardiovascular disease, but prospective evidence is scarce, imprecise, and mostly limited to coronary heart disease. We aimed to assess long working hours as a risk factor for incident coronary heart disease and stroke.METHODS: We identified published studies through a systematic review of PubMed and Embase from inception to Aug 20, 2014. We obtained unpublished data for 20 cohort studies from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium and open-access data archives. We used cumulative random-effects meta-analysis to combine effect estimates from published and unpublished data.FINDINGS: We included 25 studies from 24 cohorts in Europe, the USA, and Australia. The meta-analysis of coronary heart disease comprised data for 603,838 men and women who were free from coronary heart disease at baseline; the meta-analysis of stroke comprised data for 528,908 men and women who were free from stroke at baseline. Follow-up for coronary heart disease was 5·1 million person-years (mean 8·5 years), in which 4768 events were recorded, and for stroke was 3·8 million person-years (mean 7·2 years), in which 1722 events were recorded. In cumulative meta-analysis adjusted for age, sex, and socioeconomic status, compared with standard hours (35-40 h per week), working long hours (≥55 h per week) was associated with an increase in risk of incident coronary heart disease (relative risk [RR] 1·13, 95% CI 1·02-1·26; p=0·02) and incident stroke (1·33, 1·11-1·61; p=0·002). The excess risk of stroke remained unchanged in analyses that addressed reverse causation, multivariable adjustments for other risk factors, and different methods of stroke ascertainment (range of RR estimates 1·30-1·42). We recorded a dose-response association for stroke, with RR estimates of 1·10 (95% CI 0·94-1·28; p=0·24) for 41-48 working hours, 1·27 (1·03-1·56; p=0·03) for 49-54 working hours, and 1·33 (1·11-1·61; p=0·002) for 55 working hours or more per week compared with standard working hours (ptrend<0·0001).INTERPRETATION: Employees who work long hours have a higher risk of stroke than those working standard hours; the association with coronary heart disease is weaker. These findings suggest that more attention should be paid to the management of vascular risk factors in individuals who work long hours.FUNDING: Medical Research Council, Economic and Social 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), US National Institutes of Health, British Heart Foundation.
AB - BACKGROUND: Long working hours might increase the risk of cardiovascular disease, but prospective evidence is scarce, imprecise, and mostly limited to coronary heart disease. We aimed to assess long working hours as a risk factor for incident coronary heart disease and stroke.METHODS: We identified published studies through a systematic review of PubMed and Embase from inception to Aug 20, 2014. We obtained unpublished data for 20 cohort studies from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium and open-access data archives. We used cumulative random-effects meta-analysis to combine effect estimates from published and unpublished data.FINDINGS: We included 25 studies from 24 cohorts in Europe, the USA, and Australia. The meta-analysis of coronary heart disease comprised data for 603,838 men and women who were free from coronary heart disease at baseline; the meta-analysis of stroke comprised data for 528,908 men and women who were free from stroke at baseline. Follow-up for coronary heart disease was 5·1 million person-years (mean 8·5 years), in which 4768 events were recorded, and for stroke was 3·8 million person-years (mean 7·2 years), in which 1722 events were recorded. In cumulative meta-analysis adjusted for age, sex, and socioeconomic status, compared with standard hours (35-40 h per week), working long hours (≥55 h per week) was associated with an increase in risk of incident coronary heart disease (relative risk [RR] 1·13, 95% CI 1·02-1·26; p=0·02) and incident stroke (1·33, 1·11-1·61; p=0·002). The excess risk of stroke remained unchanged in analyses that addressed reverse causation, multivariable adjustments for other risk factors, and different methods of stroke ascertainment (range of RR estimates 1·30-1·42). We recorded a dose-response association for stroke, with RR estimates of 1·10 (95% CI 0·94-1·28; p=0·24) for 41-48 working hours, 1·27 (1·03-1·56; p=0·03) for 49-54 working hours, and 1·33 (1·11-1·61; p=0·002) for 55 working hours or more per week compared with standard working hours (ptrend<0·0001).INTERPRETATION: Employees who work long hours have a higher risk of stroke than those working standard hours; the association with coronary heart disease is weaker. These findings suggest that more attention should be paid to the management of vascular risk factors in individuals who work long hours.FUNDING: Medical Research Council, Economic and Social 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), US National Institutes of Health, British Heart Foundation.
U2 - 10.1016/S0140-6736(15)60295-1
DO - 10.1016/S0140-6736(15)60295-1
M3 - Journal article
C2 - 26298822
SN - 1474-547X
VL - 386
SP - 1739
EP - 1746
JO - Lancet
JF - Lancet
IS - 10005
ER -