5907415 epidemiology of noncommunicable diseases

8/2/2019 5907415 Epidemiology of Noncommunicable Diseases

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Epidemiology of Non-

Communicable Diseases

Adora F. Mendoza-Abat, M.D., CFP


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Definitions

Environmental Epidemiology the studyof environmental factors that influence thedistribution of diseases in the human

population

Occupational Epidemiology the study of

workplace exposures on the frequencyand distribution of diseases and injuries inthe population


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Infectious Diseases Non-Infectious Diseases

-Single necessary agent

-Specific agent-diseaserelationship

-Causes are relatively wellunderstood

-Short incubation period

-No single necessary agent

- One-to-onecorrespondence betweenagent and disease very rare

-Causes unknown,intervention usually based

on risk factors

-Long latency period


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Infectious Diseases Non-Infectious Diseases

-Single exposure usuallysufficient

-Usually produce acute

disease

-Acquired immunity possible

-Dx based on tests specificto disease agent

-May require multipleexposure to same ormultiple agents

-Most often produce

chronic disease

-Acquired immune unlikely

-Dx often dependent onnonspecific symptoms ortest


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Classification of Etiologic Agents orRisk Factors

1. Environmental Factors that may AffectHealth

A. Psychological Factors

B. Biological Factors

C. Chemical Factors

D. Physical Factors E. Accidental Factors


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Classificatn of Etiologic Agents or RiskFactors

2. Environmental Components & Health Hazards

Components Health Hazards

Physical : air, water, soil,

food, climate and weather,noise level, radiation level

Social: work, transport,

leisure, housing, family andcommunity

Physical: heat and cold,radiation, noise

Chemical: metals, chemicalsubstances

Biological: microorganisms,

flora and faunaSocial; culture/customs,interpersonal relations,social and politicalstructure, housing factors


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Environmental Hazards

1. Site and location (earthquakes, flood, wind,storms, drought)

2. Biological (animal, insect, microbiological,vegetation)

3. Chemical (poisons and toxins, allergens,irritants)

4. Physical (vibration, radiation, forces and

abrasion, humidity)5. Psychological (stress, boredom, anxiety,

discomfort, depression)

6. Sociological (overcrowding, isolation)


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Uses of Environmental / OccupationalEpidemiology

1. Identify etiologic factors2. Monitoring trends and changes on health

consequences/impact

3. Planning, management and evaluation ofprograms (projections and risk assessment)

4. Communicate information regarding

environmental hazards5. Basis for establishing safety standards or

thresholds

6. Others (eg. Elucidating mechanisms oftoxicity, describe dose-response relationships)


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Causes of Under-recognition ofOccupational/Environmental Dse.

1. Inherent difficulty in diagnosingoccupational diseases

2. Difficulty in establishing cause and effectrelationships

3. Lack/incomplete evaluation of chemicals forpotential toxicity

4. Inadequate pre-market evaluation of newlydeveloped chemical substances


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5. Long latency between occupational /environmental exposure and onset of illness

6. Lack of awareness among healthpractitioners about hazards found at work andin the environment

7. Limited ability of many workers to providean accurate report of their toxic exposures


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8. Resistance of employers to recognize thework relatedness of a disorder because of

possible litigations suits 9. Usually involves small group of people

10. Lack of knowledge about many aspects of

behavior of environmental pollutants 11. Potential difficulties in defining potential

risks


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Major Types of OccupationalDiseases

1. Lung diseases

2. Cancer

3. Skin disorders 4. Infectious diseases

5. Reproductive disorders

6. Musculo-skeletal disorders 7. Severe traumatic injuries

8. Hearing loss


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Surveillance Activities in Environmental/ Occupational Epidemiology

1. (Occupational) Hazard Surveillance

a. Provides a means of assessing toxic

occupational exposures to a population andthus of assessing risk

b. Will identify chemicals in use, the industries

and occupations where they are used, and theextent and magnitude of worker exposure

c. Also provides a means of identifying changesin the patterns of exposure and of noting

emerging toxic hazards


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Surveillance Activities in Environmental /Occupational Epidemiology

2. (Occupational) Disease Surveillance

a. Provides a means of assessing the amount

and types of occupational disease, time trendsand distribution according to geography,industry and occupation

b. Can consist of 2 types of surveillance

b.1. Biological monitoring

b.2. Medical Screening


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Biological Monitoring

The systematic collection of biologicalspecimens (blood, urine, breath, fingernails,hair, saliva) for the purpose of estimatingexposure to environmental agents and hence

determine the risk of disease before it occurs

Interpretation - requires detailed knowledge ofthe kinetics and metabolism of chemicals

Limitations: due to the rapid excretion ofcertain chemicals, only the most recentexposure to them are measurable; may reflect

recent exposure or cumulative exposure


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Medical Screening

The periodic examination (clinical orlaboratory) to detect diseases (or healthproblems) present among apparently

healthy subjects

Issues: validity, predictive values, cost-effectiveness, acceptability of procedure


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Measurements of Exposure andOutcome : Some Issues / Considerations

1. Exposures are usually measured quantitatively

2. Dimensions of exposure: level, duration, level-

duration combined3. Current Vs. long term exposures

a. Acute Effects current exposures are

relevant (e.g. London smog epidemic in 1952)b. Cumulative Effects


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2 Types of Cumulative Effects

1. Chemical / substances that accumulatein the body (e.g. cadmium)

2. Hazards with cumulative effects (e.g.radiation, noise)


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Measurements of Exposure and Outcome :Some Issues / Considerations

4. Individual measurements vary with timea. Has implications on the frequency, timeand method used to estimate exposure ordose

5. Exposure or dose varies between individualsa. Different work habitsb. Differences in the local distribution of

pollutantsc. Differences in individual absorption andexcretion rates for the chemical

. d. People with the same external dose mayend up with different internal doses

M t f E d


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Measurements of Exposure andOutcome : Some Issues /

Considerations 6. Internal dose (absorbed dose) is usually

different from external dose (environmental

measurements) 7. Dose-effect relationship the higher the

dose the more severe and intense is the effect;

data are useful for establishing safetystandards

Set safety standard at a level where the less

severe effects are prevented

M t f E d


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Measurements of Exposure andOutcome : Some Issues /

Considerations 8. Dose-Response Relationship

Response the proportion in an

exposed group that develops a specificeffect


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Environmental Exposures Doses are at concentrations far below those

experienced by workers who are directlyhandling the materials

Will require larger population for study in order

to detect the smaller health effects likely toresult

Problems with confounding variables may be

more serious Estimation of exposure doses is complicated by

the lack of routine data on air and water

pollution


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Environmental Exposures

Use of place of residence as surrogate for

exposure may lead to exposuremisclassification because population may behighly mobile

Common to use ecologic data or correlationalstudies

Longer exposure of residents to household

toxin compared to workers Children are more susceptible than working

adults since they have faster metabolism and

absorption of the toxin


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Risk Assessment

The use of epidemiological methods andprinciples to estimate the potential healthrisks of industrial or agricultural

development projects, both before theyare implemented and while they are inoperation.

Used to predict potential health problemsin the use of new chemicals ortechnologies


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Steps in Risk Assessment

1. Identify which environmental hazard may becreated by the technology or project understudy (Hazard Identification)

2. Analyze the type of health effect that each

hazard may cause (Hazard Assessment)3. Measure or estimate the actual exposure

levels for the people potentially affected,including the general population and the workforce (Measure Actual Exposure)

- Use data on environmental and biologicmonitoring, relevant hx of exposure and

changes over time


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Steps in Risk Assessment

4. Calculate the likely health risk in thepopulation

- For each hazard identified, the exposuredata for subgroups of the exposedpopulation are combined with the dose-effect and dose-response relationships


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BURDEN OF NCDs

rising trends in non-communicable diseases as aresult of demographic and epidemiologicalchanges, as well as economic globalization

increase in life expectancy combined with changesin lifestyles are leading to epidemics of non-communicable diseases (NCD), mainlycardiovascular diseases, cancer and diabetes

In 1998, NCD accounts for 63% of global deaths

43% of all DALY globally were attributed to NCD


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Non-Communicable Diseases

Includes all traditionally defined NCDssuch as CVD, cancer, chronic respiratorydiseases, mental health as well as injuries

and violence

In all WHO regions (except sub-SaharanAfrica), NCDs today constitute the largest

contributor to burden


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NCDs accounted for 60% of all deaths in1999 and 43% of all DALYs with injuriesadding 9% of all deaths and 14% of all

DALYs

By 2020, 10 out the top 15 causes ofDALYs lost will be attributable to NCDs,

mental health and injuries/violence


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The top five positions will be occupied byIschemic Heart Disease, depression, roadtraffic injuries, cerebrovascular disease

and Chronic Obstructive PulmonaryDisease (COPD)

15th place: trachea, bronchus and lung

cancers (better known as tobacco cancers)


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GROUP OF NCDs

Cancers Lifestyle-related (CVD, diabetes)

Injury (unintentional, intentional)

Genetic disorders

Disabling disorders

Occupational disorders

Nutritional conditions

Endocrine disorders Substance abuse


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REASONS FOR THEPROMINENCE OF NCD

1. Aging of the population

2. Impact of automobiles

3. Lifestyle changes

4. Tobacco addiction

-single largest cause of preventable morbidity

and mortality

5. Physical activity6. Social and behavioral factors


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A. CHARACTERISTICS OF THE AGENTe

Absence of a single necessary agent

most NCDs are classified on the basis ofmanifestations rather than on etiology (e.g.,CVD, renal disease, neoplasms)

known causes are risk factors

e.g. obesity, elevated cholesterol levels,hypertension

I. NATURAL HISTORY


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B. TIME FRAME

- take years or decades before illness is

apparent

- no multiplication of causative agent isinvolved

- multiple low-dose exposures (somechemicals)

- some conditions seem to evolvesubsequent to chronic conditions orhigh risk states such as obesity,smoking, diabetes and high bloodcholesterol


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C. NATURE OF THE DISEASE

chronic in nature

chronic disease

(1957 Commission on Chronic Disease)

permanent

leaves residual disability

caused by nonreversible pathologicalalterations

requires special training of the patientfor rehabilitation

requires long periods of supervision,observation or care.


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Chronicity

function of the long latency period

slow disease process adaptiveresponses to stresses (may bedetrimental over the long term)

CD can be chronic (e.g. rheumaticheart disease)

NCD can be acute (e.g. chemicalpoisoning)


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D. Synergism in Disease Causation

> Asbestos and lung cancer (RR=8)> Smoking + asbestos and lung

cancer (RR=90)

- Presence of synergism decreasedlatency (produce illness in the prime oflife even with low level exposures)

- Role of initiators and promoters

M j C i f


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Major Categories ofEtiological Agents

A. Occupational

B. General environmental

C. Lifestyle and Illness


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OCCUPATIONAL

- chemical

- metals and naturally occurring minerals


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Investigating occupational exposures

agent factors to be considered

size and shape of particles

route of exposure

free or compound form

organic vs inorganic form

liquid or vapor form


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environmental factorsconditions in the work environmental

that will influence the likelihood thatworkers will come in contact with anagent

general cleanliness and ventilation

lighting, temperature

Host factors lifestyle behaviors that may increase

the risk of disease from occupationalexposure to an agent

genetic constitution


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ENVIRONMENTAL

sources of exposure contamination of air, water and soil by

industrial activities or inadequate wastedisposal

lower dose of exposure than inoccupational environments

pesticides

housing materialsautomobile exhausts

radiation


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Investigating environmental exposures

dose

data on levels of exposuremobility of subjects

confounders

additional considerations

wide range of ages

length of exposure

meterological conditions

seasonal effects


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LIFESTYLE

- poverty, stress, exercise, drug and alcohol

use, nutrition


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CONTROL OF NCD

A. PRIMARY PREVENTION- removal of agent from environmental orminimizing the amount of agent present

- Protection of the susceptible host from

exposure

B. SECONDARY PREVENTION

- screening tests

C. TERTIARY PREVENTION

- lifestyle modification


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A small core of risk factors explains the increases inCVD, certain cancers and their closely linkedconditions of obesity, type II diabetes:

tobacco, diet/nutrition, physical inactivity andalcohol

A substantial proportion of chronic respiratorydiseases and death are driven by tobacco use

Alcohol is obviously a major contributor to all causesof injuries and violence


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Tobacco trends are not hopeful

There are 1.2 billion smokers in the worldwith smoking rates in 13 to 15 year oldsbeing about 20% in diverse cities fromdeveloped and developing countries

Tobacco causes 4 million deaths per year,a figure that will increase to 10 million per

year by the late 2020s The public health impact is widespread and

increasing fast in developing countries


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Trends in alcohol use:

steady increases in many developingcountries with continued very high rates of

binge drinking in many east and centralEuropean countries.

Alcohol Use


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Obesity

has tripled in youth in several Chinese cities,

and rapidly increased over the last 15 years inthe major cities of countries like Malaysia,Brazil, Indonesia and South Africa

But these have occurred as underweightpersists in the rural areas

Often underweight is common in the sameneighborhoods as obesity is increasing

Thus both being underweight and beingoverweight are associated with poverty

Ob it ( t)


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Epidemics of obesity and type II diabetes

have been well documented in mostPacific Island States and are probablyfuelled by a combination of factors:

increased imports of high fat foodsparticularly cheap off-cuts as well asincreased consumption of sodas in societieswhere physical activity levels haveplummeted.

Devastating economic impact of diabetescomplications are recently beingdetermined for several of these countries

Obesity (cont)


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The problems of obesity and diabetesare caused by many factors

Solutions similarly need to bemultidimensional and avoid focusing on

just one aspect or on behavior change

alone


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Mental health:

450 million people who suffer frommental or neurological disorders orfrom psychosocial problems such asthose related to alcohol and drug abuse

5907415 epidemiology of noncommunicable diseases

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