BIO4503 APPLIED EPIDEMIOLOGY
NON-COMMUNICABLE
DISEASES
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DEFINITION AND RELATED CONCEPTS
Def: “noncommunicable disease, (NCD) are no-transmissible
between persons, medical conditions”
Chronic vs, acute: NCDs may be chronic or acute
Some examples: autoimmune diseases, heart disease, stroke,
many cancers, asthma, diabetes, chronic kidney disease,
osteoporosis, Alzheimer's disease, cataracts, and so on
Risk factors: In opposition to infectious diseases, risk factors don’t
include an infectious agent but are found in the person’s
background: LIFESTYLE and ENVIRONMENT
SOME MACRO-FIGURES AND FACTS
• The rise of NCD started after the II WW.
• Most prevalent leading causes of disease and mortality in
developed countries
• Increased burden in low- and middle- income countries
• Already leading cause of death in developing countries!:
• MORTALITY IN 2008: 57 million1
• NCD ASSOCIATED MORTALITY IN 2008: 36 million
(2/3 of total)
• Main NCDs mortality causes:
• cardiovascular diseases,
• cancers,
• diabetes and
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• chronic lung diseases
WORLD 10 LEADING CAUSES OF
MORTALITY. 2008
Deaths
[millions]
%of deaths
Ischaemic heart disease
7.25
12.8%
Stroke and other cerebrovascular disease
6.15
10.8%
Lower respiratory infections
3.466
1%
Chronic obstructive pulmonary disease
3.285
8%
Diarrhoeal diseases
2.464
3%
HIV/AID
1.78
3.1%
Trachea, bronchus, lung cancers
1.392
4%
Tuberculosis
1.342
4%
Diabetes mellitus
1.262
2%
Road traffic accidents
1.212
1%
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NCD MORTALITY. 2011
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CRITERIA FOR CAUSATION OF CHRONIC
DISEASE. EVAN’S POSTULATES [I]
1. Prevalence of the disease should be significantly higher in those
exposed to the hypothesized cause than in controls not so exposed.
2. Exposure to the hypothesized cause should be more frequent
among those with the disease than in controls without the disease,
when all other risk factors are held constant.
3. Incidence of the disease should be significantly higher in those
exposed to the hypothesized cause than in controls not so exposed,
as shown by the prospective studies.
4. The disease should follow exposure to the hypothesised causative
agent with a normal or long-normal distribution of incubation
periods.
5. A spectrum of host responses should follow exposure to the
hypothesized agent along a logical biological gradient from mild to
severe.
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CRITERIA FOR CAUSATION OF CHRONIC
DISEASE. EVAN’S POSTULATES [II]
6. A measurable host response following exposure to the hypothesized
cause should have a high probability of appearing in those lacking this
before exposure [e.g.: antibody, cancer cell] or should increase in
magnitude if present before exposure. This response pattern should
occur infrequently in persons not so exposed.
7. Experimental reproduction of the disease should occur more
frequently in animals or humans appropriately exposed to the
hypothesized cause then in those not so exposed: this exposure may
be deliberate in volunteers, experimentally induced in the laboratory,
or may represent a regulation of the natural exposure.
8. Elimination or modification of the hypothesized cause should
decrease the incidence of the disease [e.g.: attenuation of a virus,
removal
of tar from cigarettes].
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CRITERIA FOR CAUSATION OF CHRONIC
DISEASE. EVAN’S POSTULATES [III]
9. Prevention or modification of the host’s response on exposure to the
hypothesized cause should decrease or eliminate the disease [e.g.:
immunization, drugs to lower cholesterol, specific lymphocyte transfer
factor in cancer]
10. All the relationships and findings should make biological and
epidemiological sense.
Source: Evans, AS. (1976). Causation and disease. The Henle-Koch postulated revisited.
Yale Journal of Biology and Medicine. 49:175-195
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NCD and globalisation
• NCDs are caused, to a large extent, by four behavioural
risk factors that are pervasive aspects of economic
transition, rapid urbanization and 21st-century lifestyles:
1. tobacco use,
2. unhealthy diet,
3. insufficient physical activity
4. harmful use of alcohol.
Current population-wide initiatives fall short in the global
context. E.g.: <10% of the world’s population is fully
protected by any of the tobacco demand-reduction
measures contained in the WHO Framework Convention
on Tobacco Control
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MACRO ANALYSIS OF THE FOUR
BEHAVIOURAL RISK FACTORS FOR
NCD: TOBACCO
• Almost 6 million people die from tobacco use each year,
both from direct tobacco use and second-hand smoke.
• By 2020, this number will increase to 7.5 million,
accounting for 10% of all deaths.
• Smoking is estimated to cause about 71% of lung
cancer, 42% of chronic respiratory disease and nearly
10% of cardiovascular disease.
• The highest incidence of smoking among men is in
lower-middle-income countries
• For total population, smoking prevalence is highest
among upper-middle-income countries
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MACRO ANALYSIS OF THE FOUR
BEHAVIOURAL RISK FACTORS FOR NCD:
INSUFFICIENT PHYSICAL ACTIVITY
• Approx. 3.2 million people die each year due to physical
inactivity.
• People who are insufficiently physically active have a 20%
to 30% increased risk of all-cause mortality.
• Regular physical activity reduces the risk of cardiovascular
disease including high blood pressure, diabetes, breast
and colon cancer, and depression.
• Insufficient physical activity is highest in high-income
countries, but very high levels are now also seen in some
middle-income countries especially among women.
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MACRO ANALYSIS OF THE FOUR
BEHAVIOURAL RISK FACTORS FOR NCD:
HARMFUL USE OF ALCOHOL
• Approx. 2.3 million die each year from the harmful
use of alcohol, accounting for about 3.8% of all
deaths in the world.
• More than half of these deaths occur from NCDs
including cancers, cardiovascular disease and
liver cirrhosis.
• While adult per capita consumption is highest in
high-income countries, it is nearly as high in
upper-middle-income countries.
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MACRO ANALYSIS OF THE FOUR
BEHAVIOURAL RISK FACTORS FOR
NCD: UNHEALTHY DIET
• Adequate consumption of fruit and vegetables reduces the
risk for cardiovascular diseases, stomach cancer and
colorectal cancer.
• Most populations consume much higher levels of salt than
recommended by WHO for disease prevention; high salt
consumption is an important determinant of high blood
pressure and cardiovascular risk.
• High consumption of saturated fats and trans-fatty acids is
linked to heart disease.
• Unhealthy diet is rising quickly in lower-resource settings.
Available data suggest that fat intake has been rising
rapidly in lower-middle-income countries since the 1980s.
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• Let’s see some testimonials
http://www.youtube.com/watch?v=4nHMV_420
zg
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MONITORING AND
SURVEILLANCE OF NCDs
Four main types of indicators:
Exposures
• 1. Behavioural risk factors
• 2. Physiological and metabolic risk factors
Outcomes
• 3. Mortality
• 4. Morbidity
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1. BEHAVIOURAL FACTORS
• Prevalence of current daily tobacco smoking among
adults.
• Prevalence of insufficiently active adults defined as:
– <5 times*30 minutes of moderate activity per week, or
– <3 times*20 minutes of vigorous activity per week,
– or equivalent.
• Prevalence of adult population consuming >5 grs. of
dietary sodium chloride per day.
• Prevalence of population consuming <5 total servings (400
grams) of fruit and vegetables per day.
• Adult per capita consumption in litres of pure alcohol
(recorded and unrecorded)
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2. PSYCHOLOGICAL AND
METABOLIC FACTORS
• Prevalence of raised blood glucose among adults (fasting
plasma glucose value ≥ 7.0 mmol/L (126 mg/dl) or on
medication for raised blood glucose).
• Prevalence of raised blood pressure among adults
(systolic blood pressure ≥ 140 mmHg and/or diastolic
blood pressure ≥90 mmHg or on medication for raised
blood pressure.
• Prevalence of overweight and obesity in adults and
adolescents (BMI > than 25 kg/m2 for overweight or
30kg/m2 for obesity or for adolescents according to the
WHO Growth Reference).
• Prevalence of low weight at birth (< 2.5 kg).
• Prevalence of raised total cholesterol among adults (total
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cholesterol ≥ 5.0 mmol/l or 190mg/dl).
3 MORTALITY and
4. MORBIDITY
• All-cause mortality by age, sex and region (urban
and rural, or by other administrative areas, as
available).
• Cause-specific mortality data (urban and rural, or
other administrative areas, as available).
• Unconditional probability of death between ages 30
and 70 years from cardiovascular diseases, cancer,
diabetes, and chronic respiratory diseases.
• Cancer incidence data from cancer registries, by
type of cancer.
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GLOBAL HEALTH STRATEGY
• Major global political statement on NDC: “Global
strategy for the prevention and control of non
communicable diseases”
• Endorsed by the WHA (2000).
• Three main objectives:
1. Mapping the epidemic of NCDs and their causes
2. Reducing the main risk factors through health
promotion and primary prevention approaches
3. Strengthening health care for people already
afflicted with NCDs.
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ACTION PLAN FOR THE GLOBAL
HEALTH STRATEGY. SIX OBJECTIVES1
1. To raise the priority accorded to NCD in development work at
global and national levels, and to integrate prevention and
control of NCDs into policies across all government
departments.
2. To establish and strengthen national policies and plans for the
prevention and control of NCD
3. To promote interventions to reduce the main shared modifiable
risk factors for NCD: tobacco use, unhealthy diets, physical
inactivity and harmful use of alcohol
4. To promote research for the prevention and control of NCD
5. To promote partnerships for the prevention and control of NCD
6. To monitor NCD and their determinants and evaluate progress
at the national, regional and global levels
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FRAMINGHAN HEART STUDY
Longitudinal study aiming to better understand the epidemiology
of CVD. Started in 1948 [original cohort had not yet developed
symptoms of CVD] and the on going follow up is in already its 6th
cohort.
SOME MILESTONES:
• 1960: Cigarette smoking found to increase the risk of heart disease
• 1967: Physical activity found to reduce the risk of heart disease and obesity
to increase the risk of heart disease
• 1970: High blood pressure found to increase the risk of stroke
• 1978: Psychosocial factors found to affect heart disease
• 2002: Lifetime risk of developing high blood pressure in middle-aged adults
is 9 in 10.
• 2002: Obesity is a risk factor for heart failure.
• 2010: First definitive evidence that occurrence of stroke by age 65 years in
21 a parent increased risk of stroke in offspring by 3-fold
RECOMMENDED READING
• WHA 2000. “Global strategy for the prevention and control of
NCD. Report by the Director-General: A challenge and an
opportunity”. WHA 53rd session.
• WHO (2008) “2008-2013 Action Plan for the Global Strategy
for the Prevention and Control of NCD”.
• WHO (2013) “World health statistics 2012”
• WHO (2013) “Non communicable diseases. Country profiles
2011”
• WHO (2003) “WHO Framework Convention on Tobacco
Control”
• WHO “WHO Global Strategy on Diet, Physical Activity and
Health” 2004
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RECOMMENDED READING [cont]
• Beaglehole R and Yach D (2003) Globalisation and the
prevention and control of non-communicable disease: the
neglected chronic diseases of adults. The Lancet, Volume
362, Issue 9387, 13 September 2003, p 903-908
• Banerjee A. Tracking global funding for the prevention and
control of noncommunicable diseases. Bull World Health
Organ.
At:
2012;90:479–479.
http://www.who.int/bulletin/volumes/90/7/12-108795/en/
• Alleyne G. (2011) Who’s Afraid of Noncommunicable
Diseases? Raising Awareness of the Effects of
Noncommunicable Diseases on Global Health. Journal of
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Health Communication, 16:82–93, 2011