Comparison of Waist-related Abdominal Obesity Measures: A ... · Comparison of Waist-related...

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