end2.21 - obesity dr gul bano © s nussey. what is obesity?
TRANSCRIPT
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