END2.21 - Obesity

Dr Gul Bano

© S Nussey

What is obesity?

How is obesity defined?

How to measure obesity?

BMI = Weight/height2 - using metric not Imperial measures

How to measure obesity?

cm

Who is obese?

Age and sex effects

Who is obese?

Effect of ethnic group

Who is obese?

Effect of educational level

Who is obese?

Who is obese?

Why treat obesity?

Effect of obesity on all-cause deaths

Why treat obesity?Effect of obesity on coronary disease deaths

Why treat obesity?

Effect of obesity onType 2 DM

Quantification of weight gain as a risk factor for diabetes

• US female nurses study - 114,281 - age 30-55 y with no DM, stroke, CAD or cancer at entry.

• Prospective cohort study 1976-90 (98% White).

• Outcome measure - NIDDM

• 2204 cases during 1.49 million woman-years.

• After age adjustment, BMI was the dominant predictor of NIDDM

Ann Intern Med 1995, 122: 481.

US Nurses study

1

10

100

<22 22.0-22.9

23.0-23.9

24.0-24.9

25.0-26.9

27.0-28.9

29.0-30.9

31.0-32.9

33.0-34.9

>35.0

Rel

ativ

e ri

sk a

djus

ted

for

age

Attained BMI

2.94.3

replotted

US Nurses study

0.1

1

10

100

>20.0 11.0-19.9

5.0-10.9

4.9-4.9

5.0-7.9

8.0-10.9

11.0-19.9

>20.0Rel

ativ

e ri

sk a

djus

ted

for

a

ge a

nd B

MI

at 1

8y

Loss (kg) Gain (kg)

Weight change from age 18 to 1976

Effect of weight gain from 18y to 1982 on relative risk stratified for

FHFamilyhistory

Relative Risk adjusted for Age and BMI at 18y

Loss of11-19 kg

Loss of5-10 kg

Loss/Gain5 kg

Gainof 5-9

kg

Gain of10-19 kg

Gain of>20 kg

No FH 0.47 0.9 1.0 2.3 6.1 20.1

One parent 2.1 1.9 3.6 6.8 12.6 27.9

Siblingalone

4.3 1.0 5.8 11.9 32.8

Both parentsand sibling

3.7 1.6 11.7 21.3 48.7

Quantification of weight gain as a risk factor for diabetes

• NHANES I - 14,407 US adults >25y 1971-5, followed to 1992.

• Weight change from recruitment to first follow up in 1982-4.

• Outcome measure - NIDDM

• 27% increased risk for gains of 5kg or more

• Every kg increase produces 4.5% increase in risk

Am J Epidemiol 1997, 146: 214

NHANES I Study

Weight change Relative risk corrected*

BMI <25 BMI 25-<29 BMI >29

at recruitment

Loss > 5kg 2.3 0.7 1.25

Loss <5 kg to gain <5kg 1.0 1.0 1.0

Gain 5-<8 kg 1.84 2.38 2.11

Gain 8-<11kg 1.02 1.34 1.1

Gain 11-<20 kg 3.33 2.3 2.64

Gain > 20 kg 2.83 6.1 2.3

*corrected for age, sex, race,education, smoking, cholesterol, bp, alcohol

Effects of weight loss on diabetes associated mortality

• US Cancer Prevention Study I• 1959-60 - 1,078,894 men & women age > 30y with

91% follow up to 1972.• 52,207 white women age >40 and <64y who had

never smoked and had BMI > 27 at recruitment, 15,069 with ‘obesity related health condition’ (heart disease, stroke, diabetes, hypertension).

• Outcome measure - Death certificate ICD-7 code 260

Am J Epidemiol 1995, 141:1128

Cancer Prevention Study I

Weight change Diabetes related deaths*Corrected Mortality Rate Ratios

mean 95% CI

None 1.0

Not known 1.41 1.06-1.87

Unintentional loss 0.98 0.67-1.56

Unintentional gain 1.02 0.67-1.56

Intentional loss of 0.5-9 kg 0.56 0.38-0.82

Intentional loss of >9.1 kg 0.69 0.53-0.9

*corrected for initial age and BMI, education, alcohol, physical activity, other illnesses

How to treat obesity?

Representative outcomes of therapy

Treating obesity

Overlapping activities in an integrated approach

Current potential integration

Effectiveness of lifestyle changes in general practice

• Meta-analysis - smoking, alcohol, diet and exercise.

• Randomised trials including ‘usual care’ arm, published in English.

• 6 electronic databases and 37 trials. Only smoking intervention could be analysed.

• None showed substantial changeFamily Practice 1997, 14:160

Shared Care Approach - 1

• Australian study of shared care vs hospital based

• 37 shared care vs 101 gender-, age- and BMI- matched hospital care patients.

• Food habits by questionnaire, weight, BMI with comparisons at 10 and weeks.

• Jointly designed protocol. NB fewer GPs signed up for obesity shared-care protocol than for other protocols.

Int J Obesity 1996, 20:413

Shared Care Approach - 2

Shared care Hospital based

Week 10-week 1

Weight loss (kg) 4.8 + 0.6 2.6 + 0.4

BMI 1.8 + 0.2 0.9 + 0.2

Retention 76% 59%

Week 26-week 1

Weight loss (kg) 5.0 + 1.2 5.0 + 0.9

BMI 1.9 + 0.5 1.9 + 0.4

Retention 45% 30%

Changes in BMI in the Minnesota Heart Health Program

• 6 communities in 3 states - 500,000 people

• Mass media, physician education, risk factor screening, adult education, environmental programs, youth education for 7 years in 3.

• Obesity not primary outcome but included.

• Cross-sectional and cohort studies• BMI increased with time and was

unaffected by intervention. Int J Obesity 1995, 19:30.

Changes in BMI in the Stanford 5-city project

• 2 treatment cities n=122,800 received 6 yr mass media and community cardiovascular risk reduction program.

• BMI a primary outcome• Cross-sectional and cohort

studies• BMI increased with time and

was unaffected by intervention. Am J Epidemiol 1991, 134:235

Physician

Surgeon

Psychologist

Dietitian

Community

Mechanism - 1

‘Medicalise’ the problem

Provide means

Motivate

Reinforce

Establish individual responsibility

Set individual long-term targets

Focus

Use individualised objective measures

Measure

Mechanism - 2

‘Medicalise’ the problem

Entry into main-stream medicine

Avoids suggestionof moral turpetude

Establishes patho-physiologicalmechanism

Provides mechanism by whichsocio-political issues can be addressed

Mechanism - 3

Individual Responsibility

Clear definition of risk, comparablewith smoking, bp, lipids

Motivation

Clarity of purposeand targets for therapy

Reinforces medical model

Avoids comparisons

Conclusion

• Obesity should be managed as a disease entity by a physician-centred multidisciplinary team.

• Evidence for long-term success of commercial community-based treatment is sparse.

• Evidence for the success of non-commercial community-based management (however desirable) is negligible.

Means

• Eating pattern modification– + Behaviour therapy eg eating situation – + Appetite suppression eg sibutramine– + Fat malabsorption eg orlistat– + Group therapy eg ‘Weight Watchers’– + Gastric balloon or waist cord– + Surgery eg banded gastroplasty

• Exercise

Medical treatment of obesity

• Dexfenfluramine - withdrawn

• Orlistat - fat malabsorption

• Sibutramine - centrally acting

Sibutramine

Orlistat

Conclusion

• Moderate weight loss (~10% or 10kg) is associated with - – A significant reduction in diabetes incidence and

associated mortality

– Improved metabolic control in established diabetes

• This can be achieved with medical therapies

• More significant weight loss in morbid obesity can currently only be achieved by surgical techniques