Biological and behavioural explanations of social inequalities in coronary heart disease: the Whitehall II study.
OBJECTIVE
We determined the degree to which metabolic syndrome components, inflammation and health behaviours account for the social gradient in CHD.


METHODS
A total of 5312 men, initially aged 39 to 63 years, were followed for 13.1 years for incident coronary death or non-fatal myocardial infarction according to socioeconomic position (employment grade). The contribution of explanatory factors to socioeconomic differences in CHD was assessed by the reduction in hazard ratios computed using Cox models. The effects of measurement error were taken into account.


RESULTS
Coronary events were more common in lower employment grades than in higher, with a hazard ratio (relative index of inequality) of 2.2 (95% CI 1.3-3.7), after adjustment for age and ethnic group. Behavioural risk factors (mainly smoking and diet) explained a third of the socioeconomic gradient in CHD incidence. Components of the metabolic syndrome and inflammatory markers predicted CHD incidence and also explained a third of the gradient. Combined, these two groups of predictors, i.e. behavioural and biological, accounted for over half of the socioeconomic gradient in incident CHD. Adding body height as a marker of the effects of early life increased this figure to about 60%.


CONCLUSIONS
A major question has been how someone's socioeconomic position can lead to increased risk of CHD. Socioeconomic differences in components of the metabolic syndrome (and inflammatory markers) provide part of the answer. This was, to an important degree, independent of the contribution of health behaviours to the socioeconomic differentials in CHD.
Marmot
M G
MG
Department of Epidemiology and Public Health, University College London, London, WC1E 6BT, UK. m.marmot@ucl.ac.uk
Shipley
M J
MJ
Hemingway
H
H
Head
J
J
Brunner
E J
EJ
D000328:Adult; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D002423:Cause of Death; D003327:Coronary Disease / Q000453:epidemiology* / Q000401:mortality / Q000523:psychology*; D003971:Diastole; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000453:epidemiology; D008131:London; D008875:Middle Aged; D016016:Proportional Hazards Models; D012042:Registries; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D012919:Social Behavior; D012959:Socioeconomic Factors; D013599:Systole; D049629:Waist-Hip Ratio
D002097:C-Reactive Protein
Lancet. 1997 Jul 26;350(9073):235-9
9242799
Arterioscler Thromb Vasc Biol. 2000 Jul;20(7):1842-7
10894827
Eur J Epidemiol. 2007;22(10):675-83
17668278
N Engl J Med. 2001 Jul 12;345(2):99-106
11450679
Methods Inf Med. 1990 Sep;29(4):354-61
2233383
N Engl J Med. 2004 Apr 1;350(14):1387-97
15070788
BMJ. 1997 May 17;314(7092):1472-6
9167568
J Epidemiol Community Health. 2003 Feb;57(2):147-53
12540692
J Intern Med. 2000 Feb;247(2):188-97
10692081
Int J Epidemiol. 2004 Apr;33(2):289-96
15082628
JAMA. 1998 Jun 3;279(21):1703-8
9624022
Lancet. 1991 Jun 8;337(8754):1387-93
1674771
Am J Public Health. 1994 Jun;84(6):932-7
8203689
Ann N Y Acad Sci. 1999;896:3-15
10681884
Br Med Bull. 1997 Jan;53(1):3-9
9158280
Circulation. 2002 Nov 19;106(21):2659-65
12438290
Int J Epidemiol. 2006 Aug;35(4):922-31
16565153
Int J Epidemiol. 2005 Apr;34(2):251-6
15576467
Stat Med. 2007 Jan 30;26(2):426-42
16220522
Am J Epidemiol. 2007 Apr 1;165(7):828-37
17244635
Circulation. 2005 Jun 14;111(23):3071-7
15939818
BMJ. 2007 Jul 21;335(7611):136
17615182
Diabetologia. 1997 Nov;40(11):1341-9
9389428
J Epidemiol Community Health. 1982 Jun;36(2):102-8
7119652
BMJ. 2006 Apr 15;332(7546):878-82
16510492
Circulation. 1994 Jul;90(1):583-612
8026046
Am J Epidemiol. 1996 Nov 15;144(10):934-42
8916504
N Z Med J. 1993 May 26;106(956):193-6
8341437
BMJ. 1998 May 30;316(7145):1636-42
9603745
Am J Clin Nutr. 2008 May;87(5):1414-21
18469266
Lancet. 1984 May 5;1(8384):1003-6
6143919
N Engl J Med. 2001 May 3;344(18):1343-50
11333990
Biostatistics. 2006 Apr;7(2):213-24
16192414
Lancet. 1996 Apr 13;347(9007):1008-13
8606563
Br J Nutr. 2001 Sep;86(3):405-14
11570993
Am J Public Health. 1999 Mar;89(3):315-21
10076479
BMJ. 2006 Mar 4;332(7540):521-5
16428252
Am J Epidemiol. 2002 Apr 15;155(8):683-7
11943683
Lancet. 2005 Dec 3;366(9501):1954-9
16325697
Mol Genet Metab. 2007 Apr;90(4):422-8
17123852
Int J Epidemiol. 2003 Aug;32(4):600-6
12913036
Am J Public Health. 1996 Apr;86(4):486-96
8604778
J Epidemiol Community Health. 2000 Mar;54(3):178-84
10746111
Soc Sci Med. 2003 Apr;56(7):1397-410
12614692