Original article
Body Mass Index, the Most Widely Used But Also Widely Criticized Index: Would a Criterion Standard Measure of Total Body Fat Be a Better Predictor of Cardiovascular Disease Mortality?

https://doi.org/10.1016/j.mayocp.2016.01.008Get rights and content

Abstract

Objectives

To examine whether an accurate measure (using a criterion standard method) of total body fat would be a better predictor of cardiovascular disease (CVD) mortality than body mass index (BMI).

Participants and Methods

A total of 60,335 participants were examined between January 1, 1979, and December 31, 2003, and then followed-up for a mean follow-up period of 15.2 years. Body mass index was estimated using standard procedures. Body composition indices (ie, body fat percentage [BF%], fat mass index [FMI], fat-free mass [FFM], and FFM index [FFMI]) were derived from either skinfold thicknesses or hydrostatic weighing. For exact comparisons, the indices studied were categorized identically using sex-specific percentiles.

Results

Compared with a medium BMI, a very high BMI was associated with a hazard ratio (HR) of 2.7 (95% CI, 2.1-3.3) for CVD mortality, which was a stronger association than for BF% or FMI (ie, HR, 1.6; 95% CI, 1.3-1.9 and HR, 2.2; 95% CI, 1.8-2.7, respectively). Compared with a medium FFMI, a very high FFMI was associated with an HR of 2.2 (95% CI, 1.7-2.7) for CVD mortality, with these estimates being markedly smaller for FFM (ie, HR, 1.2; 95% CI, 0.9-1.6). When the analyses were restricted only to the sample assessed with hydrostatic weighing (N=29,959, 51.7%), the results were similar, with even slightly larger differences in favor of BMI (ie, HR, 3.0; 95% CI, 2.2-4.0) compared with BF% and FMI (ie, HR, 1.5; 95% CI, 1.2-1.9 and HR, 2.1; 95% CI, 1.6-2.7, respectively). We estimated Harrell's c-index as an indicator of discriminating/predictive ability of these models and observed that the c-index for models including BMI was significantly higher than that for models including BF% or FMI (P<.005 for all).

Conclusion

The simple and inexpensive measure of BMI can be as clinically important as, or even more than, total adiposity measures assessed using accurate, complex, and expensive methods. Physiological explanations for these findings are discussed.

Section snippets

Study Design and Participants

The ACLS is a prospective epidemiologic investigation of adult men and women7, 9, 10; participants are mostly whites (98%), are well-educated, and have worked in executive or professional positions.11 All participants completed a detailed questionnaire and underwent an extensive clinical evaluation, including physical examination, fasting blood chemistry analyses, personal and family health history, body composition, smoking and alcohol use, and a maximal exercise treadmill test between January

Characteristics of the Study Sample

Table 1 summarizes the descriptive characteristics of the study sample at baseline (N=60,355): 13% (n=8091) of the participants were obese and 18% (n=7887) of them centrally obese; 16% (n=9517) of the participants were smokers; and 8% (n=4628) of them drank excessive alcohol. One-third of them were inactive, and one-fourth (n=15,316) had parental history of CVD disease, hypertension (n=16,952) or hypercholesterolemia (n=15,668). Over a mean follow-up period of 15.2 years, a total of 3780

Main Findings

The present study contributes to the existing knowledge with several major findings that have implications for clinical practice and public health applications as well as for the fundamental understanding of obesity and its adverse consequences. First, the main findings were directly related to daily clinical practice and epidemiology: (a) BMI was a stronger predictor of CVD mortality than were total adiposity markers, particularly BF% and FMI, assessed using accurate methods (including a

Conclusion

Our data support that BMI is a stronger predictor of CVD mortality as compared with accurate measures of adiposity, such as BF% and FMI. This suggests that the simple and inexpensive measure of BMI can be as clinically important as, or even more than, total adiposity measures assessed using accurate, complex, and expensive methods. Another major conclusion of this study is that FMI is a more informative measure of future CVD prognosis than is BF%. This has direct implications for clinical

Acknowledgments

We thank Jonatan R. Ruiz, PhD (University of Granada, Spain, and Karolinska Institutet, Sweden), Idoia Labayen, PhD (University of Basque Country, Spain), and Signe Altmäe, PhD (University of Granada), for comments on an earlier draft. We deeply thank Jairo Hidalgo-Migueles, BSc for his assistance with the c-index analyses performed with the R statistical software. None of these individuals received compensation for their contributions to this article. We thank the Cooper Clinic physicians and

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    Grant Support: This work was supported by the National Institutes of Health (grant nos. AG06945, HL62508, and R21DK088195).

    Potential Competing Interests: Dr Ortega has received a grant from the Spanish Ministry of Science and Innovation (grant no. RYC-2011-09011), and his current research activity is under the umbrella of the ActiveBrains project (Reference DEP2013-47540). Dr Lavie served as a Speaker and Consultant for the Coca-Cola Company (but on physical activity, exercise, and fitness and not on their products) and is author of the book, The Obesity Paradox.

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