title: Association of surrogate and direct measures of adiposity with risk of metabolic syndrome in rural Chinese women.
abstract: BACKGROUND
  Most studies linking obesity and metabolic syndrome (MS) have used body mass index (BMI) and waist circumference (WC) to measure obesity. While BMI is correlated with direct measures of total and central adiposity, it is influenced by lean body and bone mass. We hypothesize that direct measures of adiposity may help develop further insight into the link between obesity and MS, thus more accurately identifying individuals at high risk for MS.
  
  
  OBJECTIVE
  We examined how surrogate and direct measures of adiposity were associated with MS risk and if direct adiposity measures enhanced BMI and WC identification of MS risk.
  
  
  METHODS
  3,734 Chinese female twins aged 20-39 years were studied. Percent body fat (%BF) and proportion of trunk fat to total BF (%TF) were assessed by DEXA. Graphic plots and generalized estimating equations were used to examine the associations of adiposity measures with MS and its components. Concordance of adiposity measures and MS abnormalities between monozygotic (MZ) and dizygotic (DZ) twin pairs were compared.
  
  
  RESULTS
  The prevalence of MS increased for high BMI (>or=23 kg/m(2)), %BF (>or=32), WC (>or=80 cm), and (to a lesser degree) %TF (>or=50). Below those thresholds, the prevalence of MS was low (0-5.3%). %TF was independently associated with higher risk of MS and its components even after adjusting for BMI and WC. As a result, among women with normal BMI and WC, high %TF was associated with 1.3-2.0-fold elevated risk of MS components. In contrast, women with high BMI but normal WC and %TF neither have significantly increased risk of MS, nor for any component other than high BP. MZ twins showed higher concordance for MS and its components than DZ twins.
  
  
  CONCLUSIONS
  In this lean Chinese rural female sample, BMI >or= 23 and WC >or= 80 were associated with a markedly increased risk of MS, which was further enhanced by elevated %TF. Even in women with a normal BMI and WC, %TF was independently associated with MS and its components. Twin analysis findings suggest that adiposity measurements and MS risk are influenced by genetics.
authors.affiliation: Mary Ann and J. Milburn Smith Child Health Research Program, Department of Pediatrics, Northwestern University Feinberg School of Medicine and Children's Memorial Hospital and Children's Memorial Research Center, 2300 Children's Plaza, Chicago, IL 60614, USA.
authors.forename: Fengxiu
authors.initials: F
authors.lastname: Ouyang
authors.forename: Jonathan
authors.initials: J
authors.lastname: Necheles
authors.forename: Binyan
authors.initials: B
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Li
authors.forename: Xue
authors.initials: X
authors.lastname: Liu
authors.forename: Genfu
authors.initials: G
authors.lastname: Tang
authors.forename: Houxun
authors.initials: H
authors.lastname: Xing
authors.forename: Xiping
authors.initials: X
authors.lastname: Xu
authors.forename: Scott A
authors.initials: SA
authors.lastname: Venners
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Brickman
authors.forename: Katherine Kaufer
authors.initials: KK
authors.lastname: Christoffel
authors.forename: Donald
authors.initials: D
authors.lastname: Zimmerman
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Wang