title: Optimal scaling of weight and waist circumference to height for maximal association with DXA-measured total body fat mass by sex, age and race/ethnicity.
abstract: BACKGROUND
  Body mass index (BMI; weight (Wt)/height (Ht) (in kg m(-2)) and waist circumference (WC) are widely used as proxy anthropometric measures for total adiposity. Little is known about what scaling power of 'x' in both Wt(kg)/Ht(m)(x) and WC(m)/Ht(m)(x) is maximally associated with measured total body fat mass (TBFM). Establishing values for x would provide the information needed to create optimum anthropometric surrogate measures of adiposity.
  
  
  OBJECTIVE
  To estimate the value of 'x' that renders Wt/Ht(x) and WC/Ht(x) maximally associated with DXA-measured TBFM.
  
  
  METHODS
  Participants of the NHANES 1999-2004 surveys, stratified by sex (men, women), race/ethnicity (non-Hispanic whites, non-Hispanic blacks, Mexican-Americans), and age(18-29, 30-49, 50-84 years).
  
  
  METHODS
  We apply a grid search by increasing x from 0.0-3.0 by increments of 0.1 to the simple regression models, TBFM=b0+b1*(Wt/Ht(x)) and TBFM=b0+b1*(WC/Ht(x)) to obtain an estimate of x that results in the greatest R(2), taking into account complex survey design features and multiply imputed data.
  
  
  RESULTS
  R(2)'s for BMI are 0.86 for men (N=6544) and 0.92 for women (N=6362). The optimal powers x for weight are 1.0 (R(2)=0.90) for men and 0.8 (R(2)=0.96) for women. The optimal power x for WC is 0, that is, no scaling of WC to height, for men (R(2)=0.90) or women (R(2)=0.82). The optimal powers for weight across nine combinations of race/ethnicity and age groups for each sex vary slightly (x=0.8-1.3) whereas the optimal scaling powers for WC are all 0 for both sexes except for non-Hispanic black men aged 18-29y (x=0.1). Although the weight-for-height indices with optimal powers are not independent of height, they yield more accurate TBFM estimates than BMI.
  
  
  CONCLUSIONS
  In reference to TBFM, Wt/Ht and Wt/Ht(0.8) are the optimal weight-for-height indices for men and women, respectively, whereas WC alone, without Ht adjustment, is the optimal WC-for-height index for both sexes. Thus, BMI, an index independent of height, may be less useful when predicting TBFM.
authors.affiliation: Department of Epidemiology and Population Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA. moonseong.heo@einstein.yu.edu
authors.forename: M
authors.initials: M
authors.lastname: Heo
authors.forename: G C
authors.initials: GC
authors.lastname: Kabat
authors.forename: D
authors.initials: D
authors.lastname: Gallagher
authors.forename: S B
authors.initials: SB
authors.lastname: Heymsfield
authors.forename: T E
authors.initials: TE
authors.lastname: Rohan
mesh_terms: D050153:Abdominal Fat / Q000473:pathology; D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000368:Aged; D000369:Aged, 80 and over; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009765:Obesity / Q000453:epidemiology* / Q000208:ethnology / Q000473:pathology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012307:Risk Factors; D014481:United States; D055105:Waist Circumference; D044465:White People