Physicians' Academy for Cardiovascular Education

Mendelian randomization confirms association BMI and cardio-metabolic diseases

Association of Body Mass Index With Cardiometabolic Disease in the UK Biobank

A Mendelian Randomization Study

Lyall DM, Celis-Morales C, Ward J, et al. - JAMA Cardiology 2017; published online ahead of print

Background

Correlations between high BMI and cardiometabolic disease risk usually arise from observational studies. However, these studies are unable to fully account for confounding by shared risk factors, which, in contrast, can be achieved by mendelian randomization studies.

Studies comparing observational with mendelian randomization estimates of the association between BMI and coronary heart disease (CHD), stroke and type 2 diabetes mellitus (T2DM), reported discrepant ORs and showed inconsistency in terms of finding significant associations with CHD and stroke [1-3].

In this study, 119,859 usable data of the UK Biobank with was used to explore whether a true association exists between BMI and cardio-metabolic diseases in a large cohort with detailed measurements of covariates and, if so, whether BMI has a causal relationship with other health-related phenotypes.

For this, all participants completed physical, sociodemographic and medical assessments from 2006 to 2010. Non-white Europeans, participants with a relatedness coefficient >0.0442 (e.g. first cousins), cases with mismatch between reported and genetic gender or with failure at the UK Biobank quality controlling as well as individuals without genetic data, were excluded from the analysis.

A 93 single-nucleotide polymorphism (SNP) polygenic risk (PGR) score based on a genome-wide association study with 97 BMI-related loci of 339,224 individuals, including 56 newly discovered SNPs, was used [4]. Conventional mendelian randomization as well as the mendelian randomization (MR)-Egger method was used [5].

Main results

Conclusion

In a large population-based cohort study, BMI was associated with risk of hypertension, CHD, T2DM, elevated SBP and DBP based on causal mendelian randomization estimates, but not with stroke or pulse rate. These findings confirm that BMI represents an important modifiable risk factor for decreasing the risk of cardio-metabolic diseases in the general population.

References

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Find this article online at JAMA Cardiol