Obesity and lifestyle: weighing up the risks Anthony Rodgers School of Population Health The Univers

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Obesity and lifestyleweighing up the
risksAnthony RodgersSchool of Population
HealthThe University of Auckland
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General points

• Tip of the iceberg implications for monitoring
  and prevention
• Burden of disease
• Joint effects of risks of obesity and lifestyle
  risks

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Traditional cutpoints and the tip of the iceberg
Cholesterol
Body mass index
Blood pressure
4.0
2.0
Risk of coronary disease
1.0
Hyper-tension
Hyperchol-esterolaemia
Obesity
0.5
4.0
5.0
6.0
7.0
8.0
Systolic blood pressure (mmHg)
Body mass index (kg/m2)
Total cholesterol (mmol/l)
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Reduction in CV events with cholesterol lowering
in Heart Protection Study, regardless of baseline
cholesterol
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Absolute Risk of CVD over 5 years in patients by
blood total cholesterol (TC) at specified levels
of other risk factorsReference female 50 years,
SBP 110, HDL 1.6, non-smoker, no diabetes.TC
4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0
mmol/L.
The same cholesterol level means very different
things to different people
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Absolute Risk of CVD over 5 years in patients by
systolic blood pressure at specified levels of
other risk factorsreference female, TC 4.0,
HDL 1.6, non smoker, no diabetesSBP range 110,
120, 130, 140, 150, 160, 170, 180 mmHg
The same blood pressure level means very
different things to different people
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Distribution of attributable burden by exposure
levels
Blood pressure Cholesterol Body mass index
Obesity
Hypertension
Hyperchol-esterolaemia
Attributable DALYs (000s)
Exposure levels
Commonly used threshold values for current
definitions
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There is no such thing as hypertensionor
hypercholesterolaemiaor obesityor type 2
diabetes
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Stroke, CHD, CVD blood glucose
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CVD HbA1C / self-reported diabetes
Khaw et al BMJ 200132215-8
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There is no such thing as hypertensionor
hypercholesterolaemiaor obesityor type 2
diabetesand smoking is a matter of degree
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Smoking and the risk of stroke
Odds Ratio
smokers
(lt2 years)
group (no passive smoking)
1-5 cigarettes /day
gt15 cigarettes / day
Source Bonita, 1999
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Other examples
Neural tube defects Hip fracture Coronary disease
Maternal plasma folate Bone mineral density
Fruit vegetables per day (nmol/l) (g/cm2)
(quintiles)
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Implications for monitoring population health

• Measurement and reporting by traditional
  cutpoints must continue (but please, no more
  cutpoints eg. cutpoints of obesity by ethnicity)
• Population risk profiles should be estimated in a
  similar way to individual risk profiles

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• Anderson et al. Am Heart J. 1991121293-8.
• Framingham Heart Study
• 5 year CVD risk
• Sex
• Age
• Diabetes
• Smoking
• BP
• TC
• HDL
• (LVH)
• (previous CVD)

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Should we track population risk scores for
Australia?
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Implications for population health

• Population-based prevention programmes shaped by
  potential for prevention and /DALY not risk
  factor levels
• For example, high body mass vs tobacco

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2002 World Health ReportReducing risks,
promoting healthy lifewww.who.int/whrwww.thelan
cet.com
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Determination of attributable burden, taking
account of prevalence and relative risk
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Burden of disease compared to what?

• Counterfactual no exposure
• Tobacco no smoking
• Continuous risks optimal levels, theoretical
  minimum nb NOT obesity, hypertension etc
• High blood pressure 115 SD 6 mmHg
• High cholesterol 3.8 SD 1 mmol/l (147 SD 39
  mg/dl)
• High body mass index 21 SD 1 kg/m2
• Low fruit vegetables 600g ( SD 50 g) intake per
  day for adults
• Physical inactivity All having at least 2.5 hours
  per week of moderate- intensity activity or
  equivalent (4000KJ/week)

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Leading 15 risks in A regions Western Europe,
North America, rich Western Pacific countries
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Leading 10 selected risk factors and diseases or
injuries Developed (Amr A, Eur A, Eur B, Eur C,
WprA) Risk factor DALYs Disease or injury
DALYs Tobacco 12.2 Ischaemic heart
disease 9.4 Blood pressure 10.9 Unipolar
depressive disorders 7.2 Alcohol 9.2
Cerebrovascular disease 6.0 Cholesterol 7.6
Alcohol use disorders 3.5 Overweight/obesity 7.4
Dementia other CNS disorders 3.0 Low
fruit vegetables 3.9 Deafness 2.8 Physical
inactivity 3.3 COPD 2.6 Illicit drugs
1.8 Road traffic injury 2.5 Unsafe
sex 0.8 Osteoarthritis 2.5 Iron
deficiency 0.7 Trachea bronchus lung
cancers 2.4
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Burden of disease attributable to tobacco (
DALYs in each subregion)
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Disease and risk factor burden
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Proportion of all lost healthy life years in
developed countries
All DALYs (100)
Alcohol non-CV (9.1)
Tobacco (12.2)
Cholesterol (7.6)
Blood pressure (10.9)
High body mass (7.4)
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Global cardiovascular disease burden due to 6
major risk factors
Systolic blood pressure over 115mmHg 45
Cholesterol over 3.8 mmol/l 28
Inactivity 11
Fruit and vegetable under 600g/day 16
BMI gt21 kg/m2 15
Tobacco 12
Area proportional to population attributable
fraction for global DALYs, overlap not
proportional to joint effects
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Global disease burden due to leading 10 vs 20
risks

• Leading 10 Leading 20
• Attributable deaths 42 46
• Attributable DALYs 33 39
• Attributable HALE 8.4 yrs 9.2 yrs

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Conclusion

• Traditional risk factor cutpoints are essential
  for monitoring but could lead to considerable
  underestimation of prevention potential
• Joint effects of obesity and lifestyle risks
  are much greater than commonly realised
• Attribtable DALYs and /DALY can help guide
  priorities