Abstract
Research on the relationship between body mass index (BMI) and mortality has led to conflicting results; a lack of agreement about how to adjust for confounders, such as smoking status, has added to the problem. Complicating such analyses is the fact that the BMI–mortality association is not a symmetric quadratic relationship; the distribution tends to be skewed to the right, causing the optimal BMI—where mortality is at a minimum—to be overestimated. One way to overcome this problem is by transformation of the BMI distribution to normality. The authors suggest several approaches for doing so, including the use of 1/BMI, or lean body mass index, instead of BMI in modeling. Data sets on 50 cohorts from approximately 30 international studies were used to examine the association (direct, inverse, quadratic or none) between BMI and mortality and to investigate the possible interaction of smoking status. Of the 50 cohorts, 36 showed a quadratic association between BMI and mortality, 10 showed no association and 1 showed a direct association between lean BMI and mortality. Only three cohorts showed a significant interaction between BMI and smoking, which was approximately what one would expect from a 5% significance test, even if no interaction existed. The association between BMI and mortality is not changed when smoking status is ignored in a model or when data on smokers are excluded from analysis. The methodology used in this study could be extended to look for other interactions.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Rent or buy this article
Prices vary by article type
from$1.95
to$39.95
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
McGee DL, Diverse Populations Collaboration. Body mass index and mortality: a meta-analysis based on person-level data from twenty-six observational studies. Ann Epidemiol 2005; 15: 87–97.
Durazo-Arvizu R, McGee D, Li Z, Cooper R . Establishing the nadir of the body mass index–mortality relationship: a case study. J Am Stat Assoc 1997; 92: 1312–1319.
Waaler HT . Height, weight and mortality. The Norwegian experience. Acta Med Scand Suppl 1984; 679: 1–56.
Goetghebeur E, Pocock SJ . Detection and estimation of J-shaped risk–response relationships. J R Stat Soc Ser A Stat Soc 1995; 158: 107–121.
Allison DB, Faith MS . On estimating the minima of BMI–mortality curves. Int J Obes Relat Metab Disord 1996; 20: 496–498.
Cornfield J, Gordon T, Smith WW . Quantal response curves for experimentally uncontrolled variables. Bull Int Stat Inst 1961; 38: 97–115.
Kay R, Little S . Transformations of the explanatory variables in the logistic regression model for binary data. Biometrika 1987; 74: 495–501.
Nevill AM, Holder RL . Body mass index: a measure of fatness or leanness? Br J Nutr 1995; 73: 507–516.
BMI in Diverse Populations Collaborative Group. Effect of smoking on the body mass index–mortality relation: empirical evidence from 15 studies. Am J Epidemiol 1999; 150: 1297–1308.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Durazo-Arvizu, R., Cooper, R. Issues related to modeling the body mass index–mortality association: the shape of the association and the effects of smoking status. Int J Obes 32 (Suppl 3), S52–S55 (2008). https://doi.org/10.1038/ijo.2008.86
Published:
Issue Date:
DOI: https://doi.org/10.1038/ijo.2008.86
Keywords
This article is cited by
-
From bad to worse: collider stratification amplifies confounding bias in the “obesity paradox”
European Journal of Epidemiology (2015)
-
RETRACTED ARTICLE: The ‘obesity paradox’ and survival after colorectal cancer: true or false?
Cancer Causes & Control (2014)
-
Examining the BMI-mortality relationship using fractional polynomials
BMC Medical Research Methodology (2011)
-
Workshop on estimating the health burden of overweight and obesity
International Journal of Obesity (2008)
-
Which factors confound or modify the relationship between body weight and mortality?
International Journal of Obesity (2008)