title: Body mass index and incident coronary heart disease in women: a population-based prospective study.
abstract: BACKGROUND
  A high body mass index (BMI) is associated with an increased risk of mortality from coronary heart disease (CHD); however, a low BMI may also be associated with an increased mortality risk. There is limited information on the relation of incident CHD risk across a wide range of BMI, particularly in women. We examined the relation between BMI and incident CHD overall and across different risk factors of the disease in the Million Women Study.
  
  
  METHODS
  1.2 million women (mean age=56 years) participants without heart disease, stroke, or cancer (except non-melanoma skin cancer) at baseline (1996 to 2001) were followed prospectively for 9 years on average. Adjusted relative risks and 20-year cumulative incidence from age 55 to 74 years were calculated for CHD using Cox regression.
  
  
  RESULTS
  After excluding the first 4 years of follow-up, we found that 32,465 women had a first coronary event (hospitalization or death) during follow-up. The adjusted relative risk for incident CHD per 5 kg/m2 increase in BMI was 1.23 (95% confidence interval (CI) 1.22 to 1.25). The cumulative incidence of CHD from age 55 to 74 years increased progressively with BMI, from 1 in 11 (95% CI 1 in 10 to 12) for BMI of 20 kg/m2, to 1 in 6(95% CI 1 in 5 to 7) for BMI of 34 kg/m2. A 10 kg/m2 increase in BMI conferred a similar risk to a 5-year increment in chronological age. The 20 year cumulative incidence increased with BMI in smokers and non-smokers, alcohol drinkers and non-drinkers, physically active and inactive, and in the upper and lower socioeconomic classes. In contrast to incident disease, the relation between BMI and CHD mortality (n=2,431) was J-shaped. For the less than 20 kg/m2 and ≥35 kg/m2 BMI categories, the respective relative risks were 1.27 (95% CI 1.06 to 1.53) and 2.84 (95% CI 2.51 to 3.21) for CHD deaths, and 0.89 (95% CI 0.83 to 0.94) and 1.85 (95% CI 1.78 to 1.92) for incident CHD.
  
  
  CONCLUSIONS
  CHD incidence in women increases progressively with BMI, an association consistently seen in different subgroups. The shape of the relation with BMI differs for incident and fatal disease.
authors.affiliation: Cancer Epidemiology Unit, University of Oxford, Roosevelt Drive, Oxford, OX3 7LF, UK. dexter.canoy@ceu.ox.ac.uk
authors.forename: Dexter
authors.initials: D
authors.lastname: Canoy
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Cairns
authors.forename: Angela
authors.initials: A
authors.lastname: Balkwill
authors.forename: F Lucy
authors.initials: FL
authors.lastname: Wright
authors.forename: Jane
authors.initials: J
authors.lastname: Green
authors.forename: Gillian
authors.initials: G
authors.lastname: Reeves
authors.forename: Valerie
authors.initials: V
authors.lastname: Beral
mesh_terms: D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D003327:Coronary Disease / Q000453:epidemiology* / Q000401:mortality; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011446:Prospective Studies; D016019:Survival Analysis
references.citation: Stat Med. 2004 Jan 15;23(1):93-104
references.pmid: 14695642
references.citation: N Engl J Med. 1987 Nov 19;317(21):1303-9
references.pmid: 3683458
references.citation: BMC Public Health. 2009 Aug 13;9:294
references.pmid: 19678933
references.citation: Health Bull (Edinb). 1996 Sep;54(5):410-7
references.pmid: 8936810
references.citation: BMC Med Res Methodol. 2011 Jan 17;11:7
references.pmid: 21241500
references.citation: Am J Clin Nutr. 1992 Jun;55(6):1033-44
references.pmid: 1595574
references.citation: N Engl J Med. 1999 Oct 7;341(15):1097-105
references.pmid: 10511607
references.citation: BMC Med Res Methodol. 2012 Oct 23;12:161
references.pmid: 23110714
references.citation: Int J Obes (Lond). 2011 Nov;35(11):1433-41
references.pmid: 21285940
references.citation: Am J Clin Nutr. 2009 Feb;89(2):500-8
references.pmid: 19116329
references.citation: Int J Epidemiol. 1985 Mar;14(1):32-8
references.pmid: 3872850
references.citation: N Engl J Med. 2010 Dec 2;363(23):2211-9
references.pmid: 21121834
references.citation: BMJ. 2011 Feb 22;342:d671
references.pmid: 21343207
references.citation: J Am Coll Cardiol. 2006 Feb 7;47(3 Suppl):S21-9
references.pmid: 16458167
references.citation: Ann Epidemiol. 2005 Feb;15(2):87-97
references.pmid: 15652713
references.citation: PLoS Med. 2012;9(5):e1001212
references.pmid: 22563304
references.citation: Eur Heart J. 1999 Feb;20(4):269-77
references.pmid: 10099921
references.citation: N Engl J Med. 2007 Jun 7;356(23):2388-98
references.pmid: 17554120
references.citation: Int J Epidemiol. 2006 Feb;35(1):141-50
references.pmid: 16258057
references.citation: J Epidemiol Community Health. 2011 Sep;65(9):814-9
references.pmid: 20466710
references.citation: JAMA. 1995 Feb 8;273(6):461-5
references.pmid: 7654270
references.citation: Circulation. 2007 Dec 18;116(25):2933-43
references.pmid: 18071080
references.citation: Am J Epidemiol. 2005 Jul 1;162(1):42-8
references.pmid: 15961585
references.citation: Obesity (Silver Spring). 2010 Feb;18(2):377-83
references.pmid: 19629058
references.citation: N Engl J Med. 2006 Aug 24;355(8):779-87
references.pmid: 16926276
references.citation: Circulation. 2012 Jan 3;125(1):e2-e220
references.pmid: 22179539
references.citation: Obes Res. 2005 Aug;13(8):1466-75
references.pmid: 16129730
references.citation: Heart. 2011 Apr;97(7):564-8
references.pmid: 21324888
references.citation: Int J Epidemiol. 2004 Aug;33(4):751-8
references.pmid: 15105409
references.citation: BMJ. 2007 Dec 1;335(7630):1134
references.pmid: 17986716
references.citation: Lancet. 2011 Mar 26;377(9771):1085-95
references.pmid: 21397319
references.citation: Lancet. 2009 Mar 28;373(9669):1083-96
references.pmid: 19299006
references.citation: Stat Med. 1989 Sep;8(9):1051-69; discussion 1071-3
references.pmid: 2799131
references.citation: Int J Obes (Lond). 2013 May;37(5):732-9
references.pmid: 22751254
references.citation: Int J Epidemiol. 2012 Jun;41(3):861-70
references.pmid: 22253319