title: How well does the body adiposity index capture adiposity change in midlife women?: The SWAN fat patterning study.
abstract: OBJECTIVE
  The body adiposity index (BAI) is a proposed alternative to the body mass index (BMI) that has shown good cross-sectional agreement with percent body fat (%BF) in validation studies. The objective of this study was to examine the ability of BAI to track adiposity change over time in a biracial sample of midlife women.
  
  
  METHODS
  African-American (n = 159) and Caucasian (n = 206) women, aged 42-60 years, at the Chicago site of the Study of Women's Health Across the Nation were followed from 2002 to 2008. BAI and BMI were calculated from measurements taken at annual assessments. %BF was quantified using whole-body dual-energy X-ray absorptiometry. Difference scores (BAI(Δ) , BMI(Δ) , and %BF(Δ) ) quantified adiposity change over a mean of 1.6 (SD = 0.7) years. Lin's concordance correlation (ρ(c) ) and Bland-Altman limits-of-agreement assessed agreement between BAI and %BF.
  
  
  RESULTS
  In examining adiposity change, BAI(Δ) showed poor agreement with %BF(Δ) in the overall sample (ρ(c) = 0.41), African-American women (ρ(c) = 0.36), and Caucasian women (ρ(c) = 0.43). BAI(Δ) estimated %BF(Δ) with minimal bias (+0.4%) but low precision (±6.3%BF limits-of-agreement). %BF(Δ) had weaker correlations with BAI(Δ) (rs = 0.38-0.48) than with BMI(Δ) (rs = 0.48-0.59). BAI and BMI showed similar cross-sectional associations with %BF in the overall sample and within each race (rs > 0.74).
  
  
  CONCLUSIONS
  We conclude that BAI is less accurate than BMI in tracking adiposity change in midlife women, and would not be a suitable replacement for BMI in most research applications involving adiposity change.
authors.affiliation: Department of Preventive Medicine, Rush University Medical Center, Chicago, Illinois, USA. brad_appelhans@rush.edu
authors.forename: Bradley M
authors.initials: BM
authors.lastname: Appelhans
authors.forename: Rasa
authors.initials: R
authors.lastname: Kazlauskaite
authors.forename: Kelly
authors.initials: K
authors.lastname: Karavolos
authors.forename: Imke
authors.initials: I
authors.lastname: Janssen
authors.forename: Howard M
authors.initials: HM
authors.lastname: Kravitz
authors.forename: Sheila
authors.initials: S
authors.lastname: Dugan
authors.forename: John W
authors.initials: JW
authors.lastname: Burns
authors.forename: Karla
authors.initials: K
authors.lastname: Shipp-Johnson
authors.forename: Lynda H
authors.initials: LH
authors.lastname: Powell
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods*; D050154:Adiposity / Q000208:ethnology; D000328:Adult; D001741:Black or African American; D050218:Body Fat Distribution / Q000379:methods*; D015992:Body Mass Index; D002641:Chicago; D005260:Female; D006801:Humans; D008875:Middle Aged; D044465:White People