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Decomposing the educational gradient in allostatic load across European populations. What matters the most: differentials in exposure or in susceptibility?
  1. Giovanni Veronesi1,
  2. Frank Kee2,
  3. Blanaid Hicks2,
  4. Hannah Forrest1,
  5. Hugh Tunstall-Pedoe3,
  6. Kari Kuulasmaa4,
  7. Susana Sans5,
  8. Veikko Salomaa4,
  9. Barbara Thorand6,
  10. Augusto Di Castelnuovo7,
  11. Stefan Soderberg8,
  12. Giancarlo Cesana9,
  13. Martin Bobak10,
  14. Roberto De Ponti11,
  15. Licia Iacoviello1,12,
  16. Luigi Palmieri13,
  17. Tanja Zeller14,
  18. Stefan Blankenberg14,
  19. Marco M Ferrario1
  1. 1 Centro Ricerche in Epidemiologia e Medicina Preventiva, Università Degli Studi dell’Insubria, Varese, Italy
  2. 2 Centre for Public Health, Queen’s University Belfast, Belfast, UK
  3. 3 Cardiovascular Epidemiology Unit, University of Dundee, Dundee, UK
  4. 4 Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland
  5. 5 Catalan Department of Health, Barcelona, Spain
  6. 6 Institute of Epidemiology, Helmholtz Center Munich German Research Center for Environmental Health, Neuherberg, Germany
  7. 7 Clinica Mediterranea SpA, Napoli, Italy
  8. 8 Public Health and Clinical Medicine, Cardiology and Heart Centre, Umea University, Umea, Sweden
  9. 9 Centro Ricerche in Sanità Pubblica, Università Degli Studi Di Milano-Bicocca,Milano, Italy
  10. 10 Department of Epidemiology and Public Health, University College London, London, UK
  11. 11 Dipartimento di Medicina e Chirurgia, Università Degli Studi dell’Insubria, Varese, Italy
  12. 12 Department of Epidemiology and Prevention, IRCCS Neuromed, Pozzilli, Italy
  13. 13 Department of Cardiovascular, Endocrine-metabolic Diseases, and Ageing, National Institute of Health, Roma, Italy
  14. 14 Department of Cardiology, University Hospital Hamburg Eppendorf University Heart Centre, Hamburg, Germany
  1. Correspondence to Marco M Ferrario, Research Center in Epidemiology and Preventive Medicine, Department of Medicine and Surgery, University of Insubria, Via O. Rossi 9, Varese 21100, Italy; marco.ferrario{at}uninsubria.it

Abstract

Background We investigate whether socially disadvantaged individuals are more susceptible to the detrimental effects of smoking and alcohol intake on allostatic load (AL), a marker of physiological ‘wear and tear’, resulting from adaptation to chronic stress.

Methods In a cross-sectional analysis, 27 019 men and 26 738 women aged 35–74 years were identified from 21 European cohorts in the BiomarCaRE consortium. We defined three educational classes (EDs) according to years of schooling and an AL score as the sum of z-scores of eight selected biomarkers from the cardiovascular, metabolic and inflammatory systems. We used the Oaxaca-Blinder decomposition to disentangle the ED gradient in AL score into the differential exposure (DE, attributable to different distribution of smoking and alcohol intake across EDs) and the differential susceptibility (DS, attributable to a different effect of risk factors on AL across EDs) components.

Results Less-educated men (mean AL difference: 0.68, 95% CI 0.57 to 0.79) and women (1.52, 95% CI 1.40 to 1.64) had higher AL scores. DE accounted for 7% and 6% of the gradient in men and women, respectively. In men, combining smoking and alcohol intake, DS accounted for 42% of the gradient (smoking DS coefficient=0.177, 26% of the gradient; alcohol DS coefficient=0.109; 16%, not statistically significant). DS contribution increased to 69% in metabolic markers. DS estimates were consistent across age groups, irrespective of comorbidities and robust to unmeasured confounding. No DS was observed in women.

Conclusions In men, a DS mechanism substantially contributes to the educational class gradient in allostatic load.

  • Social inequalities
  • Epidemiological methods
  • Epidemiology of cardiovascular disease
  • Stress

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Footnotes

  • Correction notice This article has been corrected since it first published. Affiliation 5 has been corrected to 'Catalan Department of Health'.

  • Contributors GV, FK and MMF conceived the research question and drafted the manuscript together with BH and HF. GV conducted the statistical analyses. KK, TZ and SB are guarantors of the MORGAM/BiomarCaRE database. HT-P, SuS, VS, BT, FK, MMF, StS, GC, LI and LP are Principal Investigators of the cohorts included in the current analyses. HT-P, SuS, VS, BT, ADiC, StS, GC, LI, LP, MB, RDP, KK, TZ and SB actively contributed to the interpretation of the results and made critical revision of the manuscript drafts. All authors read and approved the final version of the manuscript.

  • Funding The BiomarCaRE Project is funded by the EU Seventh Framework Programme (FP7/2007–2013) under grant agreement HEALTH-F2-2011-278913. The activities of the MORGAM Data Centre have also been sustained by recent funding from EU FP7 project CHANCES (HEALTH-F3-2010-242244). A part of the biomarker determinations in the population cohorts was funded by the Medical Research Council London (G0601463, identification No. 80983: Biomarkers in the MORGAM Populations).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval All participating studies adhered to the Declaration of Helsinki and are responsible for ethical approval and patient consent, according to local rules at the time of study enrolment. For different study populations, the list of approvals is the following: (study name, Ethics Committee name, approval ID): Northern Sweden, Research ethic Committee of Umea University, 2012–280–32M; FINRISK 1997, Ethics Committee at National Public Health Institute of Finland, 38/96; PRIME-Northern Ireland, Office for Research Ethics Committees Northern Ireland, 06/NIR02/107; MONICA/KORA Augsburg, Ethik-Kommision Bayerische Landesarztekammer, 05004; MONICA-Brianza, Comitato Etico Azienda Ospedaliera San Gerardo - Monza, 192/2005; MATISS Study (Latina), Comitato Etico Istituto Superiore di Sanità, PRE/96/06; Moli-Sani study, Comitato Etico Università Cattolica del Sacro Cuore – Roma, Prot.Pdc.P99 (A. 931/03-138-04)/CE/2004. MONICA-Catalonia: Director/Board of the Institute of Health Studies, ID not assigned. Scottish Heart Health Extended Study (SHHEC): Tayside Health Board Dundee District, DM/CL/20.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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