Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter to the Editor
  • Published:

Body mass index and the risk of all-cause mortality among patients with nonvalvular atrial fibrillation: a multicenter prospective observational study in China; methodological issues

European Journal of Clinical Nutrition volume 71, page 1019 (2017)Cite this article

Subjects

We read with interest the article by Wan et al.1 published in European Journal of Clinical Nutrition in October 2016. The study aimed to assess the association between body mass index (BMI) and the risk of all-cause mortality among patients with nonvalvular atrial fibrillation (NVAF). It was concluded that there is a paradoxical association between BMI and all-cause mortality risk in Chinese patients with NVAF. Although such valuable study has been done, there are some methodological issues that must be considered to avoid an optimistic interpretation of the study’s results.

First, all deaths were combined into one category and thereafter the relationship between the BMI was evaluated with this aggregated outcome. The study sample and statistical power of test is improved using the aggregated outcome, but it is worth mentioning that the homogeneity of associations between the BMI and cause-specific deaths is the main assumption in combined or aggregated outcome strategy. In addition, strength and direction of associations between BMI and aggregated outcome can be systematically different from their association with cause-specific deaths.2 So, to some extent, paradoxical association between BMI and all-cause mortality risk in the aforementioned study may be due to the heterogeneity of associations between BMI and cause-specific deaths. Recently, advanced statistical tools, such as hierarchical regression models, were proposed to evaluate the association between single exposure, such as BMI, and multiple outcomes, such as cause-specific deaths.3, 4

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

References

  1. Wan H, Wu S, Wang J, Yang Y, Zhu J, Shao X et al. Body mass index and the risk of all-cause mortality among patients with nonvalvular atrial fibrillation: a multicenter prospective observational study in China. Eur J Clin Nutr 2016; 71: 494–499.

    Article  Google Scholar 

  2. Whitlock G, Lewington S, Sherliker P, Clarke R, Emberson J, Prospective Studies Collaboration et al. Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies. Lancet 2009; 373: 1083–1096.

    Article  Google Scholar 

  3. Richardson DB, Hamra GB, MacLehose RF, Cole SR, Chu H . Hierarchical regression for analyses of multiple outcomes. Am J Epidemiol 2015; 182: 459–467.

    Article  Google Scholar 

  4. Safiri S, Khazaei S, Mansori K, Sani M, Ayubi E . All cause mortality and body mass index in a young Asian occupational cohort without baseline metabolic syndrome components: Methodological issues. Int J Cardiol 2017; 229: 90.

    Article  Google Scholar 

  5. Kleinbaum DG, Klein M. Survival Analysis: A Self-learning Text. Springer Science & Business Media, 2006..

  6. Pakzad R, Ashrafi-Asgarabad A, Safiri S . The prognostic impact of uric acid in patients with severely decompensated acute heart failure; Methodological issues. J Cardiol; e-pub ahead of print 23 February 2017 doi:10.1016/j.jjcc.2017.01.001.

Download references

Author information

Authors and Affiliations

  1. Department of Biochemistry and Diet Therapy, Nutrition Research Center, School of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Tabriz, Iran

    N Karamzad

  2. Department of Public Health, Managerial Epidemiology Research Center, School of Nursing and Midwifery, Maragheh University of Medical Sciences, Maragheh, Iran

    S Safiri

  3. Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

    S Safiri

Authors
  1. N Karamzad
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. S Safiri
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to S Safiri.

Ethics declarations

Competing interests

The authors declare no conflict of interest.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Karamzad, N., Safiri, S. Body mass index and the risk of all-cause mortality among patients with nonvalvular atrial fibrillation: a multicenter prospective observational study in China; methodological issues. Eur J Clin Nutr 71, 1019 (2017). https://doi.org/10.1038/ejcn.2017.69

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/ejcn.2017.69

Search

Advanced search

Quick links