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Comparison of Waist-related pAbdominal Obesity Measures: A Simulation StudyA Simulation Study
Marike VugaDepartment of Epidemiology
Obesity Journal Club January 21, 2010
Obesity and HealthNegative impact of obesity y g p yon health is well recognized
in research and clinical practice.
Abdominal obesity is yassociated with the highest
risk and worst outcome
Different HealthHealthRisks
B dBased on Bodyon Body Frame
Abdominal Obesity and Healthy
• Abdominal obesity is strongly associated with:▫ Cardiovascular disease▫ Cardiovascular disease
• also associated with:also associated with:▫ Diabetes▫ Cancer▫ Psoriasis▫ Adverse pregnancy outcomes▫ Earlier mortality in old age
Practical Abdominal Obesity Measures
Two types:• Two types:
▫ Waist-Related Measures▫ Waist-Related Measures
▫ Waist-Unrelated MeasuresWaist Unrelated Measures
Practical Waist-RelatedAbdominal Obesity MeasuresAbdominal Obesity Measures
Waist Circumference• Waist Circumference• Waist to Hip Ratio (WHR)• Waist to Height Ratio (WHtR)• Waist to Height Ratio (WHtR)• Waist to Thigh Ratio (WTR)• Conicity Index (C)• Conicity Index (C)• Abdominal Volume Index (AVI)
Abdominal Obesity Assessmenty
The best practical way to assess abdominal • The best practical way to assess abdominal obesity is still a topic of debate.
How to best measure abdominal obesity?
Waist Circumference
• Waist circumference measures
▫ the circumference around the waist around the waist
Waist to Hip Ratiop
• Waist to Hip Ratio (WHR) is based on
▫ the ratio of the circumferences around the waist and the hiparound the waist and the hip
WHR=waist/hip
Waist to Height Ratiog
• Waist to Height Ratio (WHtR) is based on
▫ the ratio of the circumferences around the waist and the heightaround the waist and the height
WHtR=waist/height
Waist to Thigh Ratiog
• Waist to Thigh Ratio (WTR) is based on
▫ the ratio of the circumferences around the waist and the Thigharound the waist and the Thigh
WTR=waist/thigh
Conicity Indexy
• Conicity Index (C) is based on▫ the volume estimate of the ▫ the volume estimate of the
body constructed between the shapes of a cylinder and a p ydouble cone.
(m)ncecircumfereWaist
(m)Height(kg)Weight0.109
(m)ncecircumfereWaistIndexConicity
( )g
Abdominal Volume Index
• Abdominal Volume Index (AVI) is based onis based on▫ the volume estimate of the
waist hip body region as a waist hip body region as a truncated cone.
AVI=[2(waist)2+0.7(waist-hip)2]/1000
Abdominal Obesity Measures:What Body Frame Measures Are Involved?y
Measure Waist Hip Thigh Height Weight
W i t YES NO NO NO NOWaist YES NO NO NO NO
WHR YES YES NO NO NO
WHtR YES NO NO YES NO
WTR YES NO YES NO NOWTR YES NO YES NO NO
Conicity YES NO NO YES YES
AVI YES YES NO NO NO
Abd i l Ob i MAbdominal Obesity Measures:Number of Body Frame MeasuresyMeasure Waist Hip Thigh Height Weight No
W i t YES NO NO NO NO 1Waist YES NO NO NO NO 1
WHR YES YES NO NO NO 2
WHtR YES NO NO YES NO 2
WTR YES NO YES NO NO 2WTR YES NO YES NO NO 2
AVI YES YES NO NO NO 2
Conicity YES NO NO YES YES 3
Abdominal Obesity Measures:Abdominal Obesity Measures:Decomposition Body Frame Measures
Measure Waistx
Hipy
Heightz
Thight
Weightw
Factor*
Op.
Waist x
WHR x 1/y *
AVI 2.7 x2 0.7 (y2-2xy) 0.001 +
WHtR x 1/z */
WTR x 1/t *
Conicity x √z 1/√w 9.17 *
Abdominal Obesity MeasuresImpact of Body Frame MeasuresImpact of Body Frame Measures
To understand the behavior of these abdominal • To understand the behavior of these abdominal obesity measures with respect to body frame, 3D graphs were compiled.graphs were compiled.
Abdominal Obesity Measures2D Graphs 2D Graphs
Functions of Waist• Functions of Waist
• Functions of Hip• Functions of Hip
• Functions of Height• Functions of Height
Waist as a Function of WaistWaist Function
200
160
180
200
100
120
140
60
80
60 80 100 120 140 160 180 200Waist Circumference (cm)
60 80 100 120 140 160 180 200
AVI as a Function of WaistAVI Waist Function
120000
80000
100000
120000
40000
60000
0
20000
60 80 100 120 140 160 180 200Waist Circumference (cm)
60 80 100 120 140 160 180 200
AVI as a Function of Hipp
AVI Hip Function
20000
30000
10000
20000
0
10000
0
Hip Circumference (cm)
80 100 120 140 160 180 200
WHR as a Function of Hipp
WHR Hip Function
0.0110.0120.013
0.0080.0090.010
0.0050.0060.007
Hip Circumference (cm)
80 100 120 140 160 180 200
WHtR as a Function of Heightg
WHtR Height Function0 75
0.650.700.75
0.500.550.60
0.350.400.45
Height (m)
1.4 1.6 1.8 2.0 2.2 2.4 2.6
Conicity as a Function of Heighty g
C Height Function1 65
1.501.551.601.65
1 301.351.401.45
1.151.201.251.30
Height (m)
1.4 1.6 1.8 2.0 2.2 2.4 2.6
Abdominal Obesity Measures3D Graphs 3D Graphs
Waist by hip• Waist by hip
• Waist by height• Waist by height
• Waist by weight• Waist by weight
Waist
Waist Hip
Waist to Hip Ratio
Waist Hip
Abdominal Volume Index
Waist Hip
Weight=70 kg (154 lbs) Height=1.8 m (5.9 ft)
Conicity Index
Waist Hip
Weight=40 kg (88 lbs) Height=1.5 m (4.9 ft)
Conicity Index
Waist Hip
Weight=100 kg (220 lbs) Height=1.7 m (5.6)
Conicity Index
Waist Hip
Weight=150 kg (330 lbs) Height=1.7 m (5.6 ft)
Conicity Index
Waist Hip
Weight=200 kg (440 lbs) Height=1.7 m (5.6 ft)
Conicity Index
Waist Hip
Abdominal Obesity Measures3D Graphs 3D Graphs
• Waist by hip
• Waist by height
• Waist by weight
Waist to Height Ratio
1.14
0.840 8
0 540.54
0.24
Waist Height
Weight=40 kg (88 lbs)
Conicity Index
Waist Height
Weight=100 kg (220 lbs)
Conicity Index
Waist Height
Weight=150 kg (330 lbs)
Conicity Index
Waist Height
Weight=200 kg (440 lbs)
Conicity Index
Waist Height
Abdominal Obesity Measures3D Graphs 3D Graphs
Waist by hip• Waist by hip
• Waist by height• Waist by height
• Waist by weight• Waist by weight
Height=1.7 m (5.6 ft)
Conicity Index
Waist Weight
Height=1.5 m (4.9 ft)
Conicity Index
Waist Weight
Height=1.9 m (6.2 ft)
Conicity Index
Waist Weight
Capture Circumference around the waist?
Waist Circumference by Gendery
Waist Circumference by Gendery
Waist Circumference by Body Sizey y
Waist Circumference by Body Sizey y
Waist Circumference
Waist circumference cut off values• Waist circumference cut off values
• Abdominal Obesity component within the • Abdominal Obesity component within the Metabolic Syndrome classification:
▫ By gender▫ By ethnic groups
Grundy et al. Circulation.2004;109:433-438.
Waist Circumference
Waist circumference has some merit• Waist circumference has some merit• may not be ideal because it depends
on body compositionon body composition
WHR > 1WHR < 1
Capture waist relative to hip circumference?
Skin fold Thickness
Waist to Hip Ratio by Body Sizep y y
short tall
Waist to Hip Ratiop
• Waist to hip ratio has some meritmay not always estimate abdominal obesity well• may not always estimate abdominal obesity well
▫ underestimate in heavy people who also have a ▫ underestimate in heavy people who also have a large hip circumference
▫ overestimate in very thin people with straight body shape (and a low hip circumference)
Capture waist relative to height?
Waist to Height Ratiog
short tall
Waist to Height Ratiog
• Waist to height ratio attempts to measure Waist to height ratio attempts to measure abdominal obesity relative to height.
▫ this seems to account in some way for body frame
Capture waist relative to Thigh?
Waist to Thigh Ratiog
Waist to Thigh Ratiog
• Waist to Thigh ratio attempts to measure Waist to Thigh ratio attempts to measure abdominal obesity relative to Thigh circumference.
▫ Depends on body composition and overall pattern f b d f di ib iof body fat distribution
Capture body volume with respect to waist?
Conicity Indexy
Conicity index is a promising abdominal • Conicity index is a promising abdominal obesity measure because it attempts to model the volume of the body with particular the volume of the body with particular emphasis on the impact of the abdominal region
Capture abdominal/hip region volume?
Abdominal Volume Index
• Abdominal Volume Index is Abdominal Volume Index is a promising abdominal obesity measure because it yattempts to model the volume of the abdomen/hip area
Conculsion
• Although many abdominal obesity are used in research only few involve relevant body frame research, only few involve relevant body frame aspects
• Among all measures, Waist to Height Ratio, Conicity Index, and AVI show the most promisey , p
Outlook
• Next step: A method comparison study to compare these measures using real datacompare these measures using real data.
• A thorough comparison of all these measures in • A thorough comparison of all these measures in terms of their predictability of relevant adverse health events using Receiver Operator Curves is g pwarranted to guide policymaking and address the question which of these measures is most b fi i l f h d li i l ibeneficial for research and clinical practice.
Although we till are still
looking for the best measure,measure,it is healthyto eat to eat an apple
and lookand look like an apple core
A k l dAcknowledgement
• Kim Sutton-Tyrrell• Ripu Jindal• Ripu Jindal• Baqiyyah Conway• Emma Barinas-MitchellEmma Barinas Mitchell• Rodolfo Valdez• Mark Woodward• Anyone involved in abdominal obesity assessment
Thank you for your attention
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