A Mendelian randomization analysis conducted by Børge Nordestgaard of Copenhagen University Hospital, Denmark and colleagues, using data from observational studies, supports a causal relationship between body mass index (BMI) and risk for ischemic heart disease (IHD). The findings, published in this week's PLoS Medicine, have important implications for public health policy because they show that the association between BMI (which is modifiable by lifestyle changes) and IHD is continuous. This means that any increase in BMI increases the risk of IHD; there is no threshold below which a BMI increase has no effect on IDH risk.
The authors state: "This analysis demonstrates the value of observational studies and their ability to provide essentially unbiased results because of inclusion of genetic data avoiding confounding, reverse causation, and bias."
Funding: Supported by the Copenhagen County Foundation and by Herlev Hospital, Copenhagen University Hospital. These sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or in preparation, review, or approval of the manuscript. TMP, NJT, and GDS work within and are funded by the MRC Centre for Causal Analyses in Translational Epidemiology, which is capacity funded by grant G0600705. BGN, TMP, MB, and NJT had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Competing Interests: George Davey Smith is on the PLoS Medicine Editorial Board. The authors have declared that no other competing interests exist.
Citation: Nordestgaard BG, Palmer TM, Benn M, Zacho J, Tybjærg-Hansen A, et al. (2012) The Effect of Elevated Body Mass Index on Ischemic Heart Disease Risk: Causal Estimates from a Mendelian Randomisation Approach. PLoS Med 9(5): e1001212. doi:10.1371/journal.pmed.1001212
CONTACT:
Børge Nordestgaard
Department of Clinical Biochemistry
Herlev Hospital
Copenhagen University Hospital
Copenhagen
Denmark
Boerge.Nordestgaard@regionh.dk
Nicholas Timpson
MRC Centre for Causal Analysis in Translational Epidemiology
University of Bristol
Bristol
United Kingdom
n.j.timpson@bris.ac.uk
Journal
PLoS Medicine