Is BMI a valid measure of obesity in post-menopausal women?

Details

• Alternative Title:
  Menopause
• Personal Author:
  Banack, Hailey R. ; Wactawski-Wende, Jean ; Hovey, Kathleen M. ; Stokes, Andrew
• Description:
  Objective
  
  Body mass index (BMI) is a widely used indicator of obesity status in clinical settings and population health research. However, there are concerns about the validity of BMI as a measure of obesity in post-menopausal women. Unlike BMI, which is an indirect measure of obesity and does not distinguish lean from fat mass, dual energy x-ray absorptiometry (DXA) provides a direct measure of body fat and is considered a gold standard of adiposity measurement. The goal of this study is to examine the validity of using BMI to identify obesity in post-menopausal women relative to total body fat percent measured by DXA scan.
  
  Methods
  
  Data from 1329 post-menopausal women participating in the Buffalo OsteoPerio study were used in this analysis. At baseline, women ranged in age from 53 years to 85 years. Obesity was defined as BMI >30kg/m2 and body fat percent (BF%) greater than 35%, 38% or 40%. We calculated sensitivity, specificity, positive predictive value and negative predictive value to evaluate the validity of BMI defined obesity relative BF%. We further explored the validity of BMI relative to percent body fat using graphical tools, such as scatterplots and receiver operating characteristic (ROC) curves. Youden’s J index was used to determine the empirical optimal BMI cut point for each level of BF% defined obesity.
  
  Results
  
  The sensitivity of BMI-defined obesity was 32.4% for 35% body fat, 44.6% for 38% body fat and 55.2% for 40% body fat. Corresponding specificity values were 99.3%, 97.1% and 94.6%, respectively. The empirical optimal BMI cut-point to define obesity is 24.9kg/m2 for 35% BF, 26.49 kg/m2 for 38% BF and 27.05 kg/m2 for 40% BF according to the Youden Index.
  
  Conclusions
  
  Results demonstrate that a BMI cut-point of 30 kg/m2 does not appear to be an appropriate indicator of true obesity status in post-menopausal women. Empirical estimates of the validity of BMI from this study may be used by other investigators to account for BMI-related misclassification in older women.
  
  
• Subjects:
  Absorptiometry, Photon Adipose Tissue Aged Body Mass Index Cohort Studies Female Humans Middle Aged Obesity Postmenopause Predictive Value Of Tests Reproducibility Of Results Women's Health

  More +
• Keywords:
  BMI Body Fat Obesity Postmenopausal Women Validation Study
• Source:
  Menopause. 25(3):307-313
• Pubmed ID:
  29135897
• Pubmed Central ID:
  PMC5821529
• Document Type:
  Journal Article
• Funding:
  R03 SH000037/SH/NCHS CDC HHSUnited States/ ; N01WH32122/WH/WHI NIH HHSUnited States/ ; HHSN268201600002C/HL/NHLBI NIH HHSUnited States/ ; HHSN268201600018C/HL/NHLBI NIH HHSUnited States/ ; R01 DE013505/DE/NIDCR NIH HHSUnited States/ ; CIHRCanada/ ; HHSN268201600003C/HL/NHLBI NIH HHSUnited States/ ; HHSN268201600004C/HL/NHLBI NIH HHSUnited States/ ; HHSN268201600001C/HL/NHLBI NIH HHSUnited States/
• Volume:
  25
• Issue:
  3
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:a56a7b4399672154df9da59cd445466873181f00b7ecf2886530f78df1404a14
• Download URL:
  https://stacks.cdc.gov/view/cdc/52056/cdc_52056_DS1.pdf
• File Type:
  [PDF - 971.88 KB ]