April 2011 1

POPULATION HEALTH: Health determinants, Prevention &

Health promotion

Ian McDowellBased on earlier presentations by R.A. Spasoff &

N. BirkettEpidemiology & Community Medicine

Other resources: SIM web site ; Toronto Notes

April 2011 2

MCC Objectives: Population health 78-1 Concepts of health and its determinants

As defined by Health Canada and the World Health Organization: 1. discuss alternative definitions of health, wellness, illness, disease and

sickness;2. describe the determinants of health. 3. explain how the differential distribution of health determinants

influences health status, and 4. explain the possible mechanisms by which determinants influence

health status.5. Discuss the concept of life course, natural history of disease,

particularly with respect to possible public health and clinical interventions.

6. Describe the concept of illness behaviour and the way this affects access to health care and adherence to therapeutic recommendations.

7. Discuss how culture and spirituality influence health and health practices, and how they are related to other determinants of health.

April 2011 3

Objective 1: Definitions of Health

A state characterized by anatomic, physiologic and psychologic integrity; ability to perform personally valued family, work and community roles; ability to deal with physical, biologic, psychologic and social stress..."  (Stokes J. J Community Health 1982;8:33-41)

“Medical model”Practical, but often criticized as too narrow

A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. (WHO, 1948)

Classic; concerns over how to measure

The ability to identify and to realize aspirations, to satisfy needs, and to change or cope with the environment. Health is therefore a resource for everyday life, not the objective of living. Health is a positive concept emphasizing social and personal resources, as well as physical capacities. (WHO Europe, 1986]

Dynamic view; a capacity rather than a state

April 2011 4

WHO (1980): International Classification of Impairments, Disabilities & Handicaps (ICIDH)

• Impairment = loss or abnormality of psychological, physiological, or anatomical structure or function (e.g., eye injury)

• Disability = resulting loss of ability to function, perform normal activities (can’t see)

• Handicap = resulting disadvantage due to inability to perform social roles (loses driving license, so perhaps job)

WHO (2001): Critique of negativity of above leads to International Classification of Function (ICF). Similar concepts, renamed impairments, activities & functions. Emphasizes importance of environment in which person lives.

Definitions of Disability, etc

April 2011 5

DiseaseDiscussion over conceptions of what is a disease:• Pathological process? Abnormal condition?

Illness causing discomfort?• Different nosologies evolve over time

– Syndrome vs. disease • “Each civilization defines its own diseases…”

(Illich)• “Non-diseases” (Richard Smith): burnout, senility,

baldness, jet lag, etc. Things doctors should probably not be treating, but patients hope they will

April 2011 6

Disease onset

signs &symptoms

consequences

(loss or abnormalityof structure or function)

Impairment

(restriction in performing a function)

Disability;Activity

(disadvantage; loss of

involvement)

Handicap;Participation

(something the doctordiagnoses and treats)

Disease

(the patient’sexperience

of beingunwell)

Illness

(socially defined status of people

who are ill)

Sickness

Time line

Leve

l of

impa

ct

Cellular

Socialfunction

Diagnosis

(WHO terms in red)

(Susser’s terms in green)

Assembling these concepts

April 2011 7

• Determinants can be seen as underlying social forces that affect large groups of people– ‘Causes of the causes’ of disease– E.g. poverty levels; policies; food prices; doctor

shortage; GNP; …– May set the incidence rates of disease in society

• Risk factors largely operate at individual level (age, genetics, health behaviours, etc)– Affect whether a person is above or below the average

risk for their age & sex

Objective 2: Determinants

April 2011 8

Income and Social Status

Social Support Networks

Education and Literacy

Employment / Working Conditions

Social Environments

Physical Environments

Personal Health Practices and Coping Skills

Healthy Child Development

Biology and Genetic Endowment

Health Services

Gender

Culture

Health Canada’s list of determinants

Note that this list blendsindividual and societalfactors. But it may be the basis for the exam!

April 2011 9

Objectives 3 & 4: Differential socioeconomic impact of health determinants

• Individual Poverty associated with increased incidence of virtually all health problems, often working through known risk factors (smoking, obesity, etc).

• On a population level, Income inequality is a major factor in richer nations: refers to the extent of disparities in income in a society (the spread, or standard deviation, of incomes).

– The broader the spread of income (even if the overall average is the same), the worse the life expectancy & other health indicators.

– Seems to operate through decreased social cohesion, community investment, less supportive legislation, less caring society, etc. (No Turnbulls!)

April 2011 10

Objective 5: Concept of Life CourseBiological programming hypothesis notes long term, cumulative health effects of

early exposures at critical periods (during gestation, childhood, adolescence). Alternative to the lifestyle explanation of chronic disease. “Embodiment”: extrinsic factors inscribed into body functions or structures.

Life course approach blends these 2 conceptions: both are important.Descriptive perspective: • 0 – 45 = age of misadventure (morbidity from injuries)• 45 – 75 = age of premature degenerative diseases• 75+ = age of senescenceAnalytic perspective: • Health is determined by cumulative impact of insults at critical developmental

times + lifetime behaviors, exposures & compensating coping mechanisms (themselves determined by early experiences). “Accumulation of risk model”

• Child rearing & patterning of behaviours that become risk factors. Links to SES. – Bowlby: early child attachment determines susceptibility to later psychiatric disorders– Eepigenetic influences on neural development that establish set points for a range of

physiological parameters – Barker hypothesis: under-nutrition in utero ‘programs’ the structure & function of body

systems and affect later risk of CVD & diabetes

April 2011 11

Objective 5: Natural history & interventions

• Distinguish between natural history & clinical course

• Links to stages of prevention

April 2011 12

Pre- and post-disease stages

Diagnosis

Initialoutcome

SymptomsBiological onset of disease

Preclinical Phase

Clinical Phase

Therapy

Longer-termoutcome: Impact on

familywork;

economic impact, etc.

Post-clinical PhaseSocial &

EnvironmentalDeterminants

Risk & Protective

Factors

Living environment

↑Community

circumstances(services

available, etc.)

↑Conditions in

society (economic

stability, etc.)

Personalfactors:

Lifestyle;Genetics;

Education;Occupation;

Socialsupports,

etc.

Clinical Course of a Disease:

HandicapImpairment Disability

Etiological Phase

April 2011 13

Preclinical phase

Clinical phase Post-clinical phaseSocial &

environmentaldeterminants

Risk & protective

factors

Etiological Phase

Primordialprevention:

Alter societalstructures& therebyunderlying

determinants

Primaryprevention:

Alter exposuresthat lead

to disease

Secondaryprevention:Detect &

treat pathological

processat an earlierstage whentreatment

can be moreeffective

Tertiaryprevention:

Preventrelapses &

furtherdeterioration

viafollow-up care& rehabilitation

April 2011 14

Objective 6: Illness Behavior1. Utilization of curative services, may seek care

early or may delay (avoidance, denial)

2. Coping mechanisms, change in daily activities

3. Factors affecting adherence to therapy

4. Describe one or more models of behaviour change, including predisposing, enabling and re-enforcing factors

a. Understand the Health Belief Model

b. ‘Stages of change model’ (aka trans-theoretical model)

April 2011 15

Perceived Susceptibility to Disease

· Demographics (age, sex, ethnicity, etc.) · Socio-psychological variables (personality, social class, peer and reference group pressures, etc.)· Structural variables (knowledge about the disease, prior experience of it, etc.)

Perceived Threat of the Disease

· Raised awareness (e.g., mass media campaign, newspaper article )· Personal advice (e.g., reminder from health professional)· Personal symptoms· Illness of family member or friend

Perceived benefits of taking action, minusPerceived barriers to

action

Likelihood of TakingRecommended Health Action

Modifying Factors

Perceived Severity of Disease

Cues to Action

April 2011 16

Precontemplation

StableLifestyle

Contemplation

PreparationAction

Maintenance

Relapse

Stages of Change “Transtheoretical” model

April 2011 17

Objective 7: Culture & Spirituality

• Culture = shared knowledge, beliefs, and values that characterize a social group. Learned through socialization.

• Cultural sensitivity = understanding the values and perceptions of your culture and how this may shape your approach to patients from other cultures.

• Cultural competence = attitudes, knowledge, and skills of practitioners necessary to become effective health care providers for patients from diverse backgrounds.

• Cultural safety goes a step beyond accepting differences, to appreciating the power imbalances and possible discrimination that exist, & treating people with respect

April 2011 18

MCC Objectives: Population health 78-3 Interventions at the population level

Enabling objectives: • Define the concept of levels of prevention at individual (clinical) and population levels• Name and describe the common methods of health protection (such as agent-host-environment approach

for communicable diseases, and source-path-receiver approach for occupational/environmental health). • Apply the principles of screening and be able to evaluate the utility of a proposed screening intervention,

including being able to discuss the potential for lead-time bias and length-prevalence bias. • Understand the importance of disease surveillance in maintaining population health and be aware of

approaches to surveillance. • Describe the advantages and disadvantages of identifying and treating individuals versus implementing

population-level approaches to prevention. • Identify ethical issues with the restricting of individual freedoms and rights for the benefit of the

population as a whole • Describe the five strategies of health promotion as defined in the Ottawa Charter and apply them to

relevant situations. • Identify the potential community social, physical and environmental factors that might promote healthy

behaviours, as well as ways to assist communities in addressing these factors.• Be aware of the role of, and work collaboratively with, community and social service agencies (e.g.

schools, municipalities and non-governmental organizations).• Demonstrate awareness of the contribution of allied professionals such as social workers in addressing

population health issues.• Be able to describe the health impact of community-level interventions to promote health and prevent

disease.• Describe examples of public policies which have had an effect on population health.

April 2011 19

Levels of Prevention

• Categories are not black and white.• Primary prevention:

– Strategies applied BEFORE disease starts.– E.g. Immunization

• Secondary prevention:– Early identification of disease– Screening; thrombolytic therapy of MI– Some people suggest secondary prevention

relates to reducing the severity of disease.

• Tertiary prevention:– Treatment and rehabilitation of disease

April 2011 20

The ‘epidemiologic triad’ of causal factors

Agent

HostEnvironment

(virulence; infectivity;addictive qualities;familiarity of a food, etc.)

(genetic susceptibility;resiliency; nutritional

status; education;motivation, etc.)

(public health sanitation; social context; availability

of health care, etc)

(Recall the fireman’s mantra: a fire requires air, fuel and heat)

April 2011 21

Health Protection• Wide range of activities undertaken by public health

departments & government agencies, such as the Public Health Agency of Canada (PHAC).

• Includes primordial and primary prevention, such as – "ensuring safe food and water supplies, providing advice to

national food and drug safety regulators, protecting people from environmental threats, and having a regulatory framework for controlling infectious diseases in place. Ensuring proper food handling in restaurants and establishing smoke-free bylaws are examples of health protection measures."

• Public health protection deals with reducing threats to the health of the population, such as biological, chemical, or physical agents

• Legislation covers identified threats, which can be detected via surveillance systems. – Public health policies & healthy public policies.

April 2011 22

Source Path(s) Receiver

ModifyRedesign

SubstituteRelocateEnclose

AbsorbBlockDilute

Ventilate

EncloseProtect

Relocate

Potential approaches to risk control

Source-Path-Receiver model for Occupational / Environmental health protection

April 2011 23

Screening• Can either:

– Detect pre-disease states (e.g. dysplasia)– Detect the disease at an early stage

• Criteria for when screening is useful– Disease criteria

• Serious: Disease causes significant morbidity, mortality • Early detection can alter the course of the disease

– Criteria related to the screening test • Valid test: high sensitivity (and specificity if possible) • Safe, rapid, cheap, acceptable

– Health care System criteria• Adequate capacity for follow-up & treatment

April 2011 24

DeathDisease onset

Appearance of 1st symptoms

Detectable by screening

Apparent increase in life expectancy or lead time

Time

Survival after diagnosis

Survival after screening

Evaluating a screening program: the hazard of Lead Time bias

No screening

Screening

April 2011 25

Screening identifies 2 cases of rapidly progressive disease and 5 cases of slowly progressive disease

Screening

Slowly progressive disease

Rapidly progressive disease death

Disease onset

Legend

Note:The incidence of rapidly progressive disease is equal to that of slowly progressive disease

Lengthbias

April 2011 26

Strategies for Prevention:High Risk Approach

• Identify individuals at high risk and attempt to reduce their risk, by changing behaviour, etc.

• Logical: high risk people should be motivated to change• But it may require testing larger population (costs, false

positives)• Asks targeted people to act differently from their peers• It may also miss many cases depending on how you define

‘high risk.’ (Mostcases typically occur in medium-risk people:see next slide)

April 2011 27

BMI≥ 35

30 to 34.9

25 to 29.9

23 to 24.9

< 23

X 32 % = 129,280 cases

X 21 % = 274,700 cases

X 10 % = 418,500 cases

X 7 % = 157,800 cases

X 3 % = 61,400 cases

BMI distribution in the Canadian

population (2007)

Individual risk of diabetes

over 10 years

Population burden: new cases of diabetes

2007–2017X

Data source: ICES report, June 2010: How many Canadians will be diagnosed with diabetes between 2007 and 2017?

=

13 %

41 %

22 %

20 %

12 % of total

26 %

40 %

15 %

6 % of total

April 2011 28

Strategies for Prevention: Population Approach

• Attempts to shift distribution of risk factor in whole population

• Gets to root of the problem

• Shades into health promotion

• Benefits everyone

April 2011 29

0500

10001500200025003000350040004500

Tubercle bacillusdiscovered

Chemotherapydeveloped

BCGvaccination

Annual TB deathsper million population

Historically, non-specific population approaches have had major impact

April 2011 30

Health PromotionDistinguishable from disease prevention in that it:• Focuses on enhancing health (via resiliency) rather

than avoiding illness• Takes a broad perspective, covering a range of

issues: not a single pathology.• Aims to tackle ‘upstream’ factors, enhancing

personal resiliency & coping skills.• Uses a participatory approach: active community

involvement; often grass roots groups.– Partnerships with NGOs, Non-Profit groups,

community agencies, social workers, etc. – Public health physician roles = advocacy, support.

April 2011 31

• Health promotion can be effective in addressing physical or social environmental hazards, (e.g., pollution, poverty), usually through community mobilization

• Environmental interventions are usually more effective than behavioural ones

• = Emphasis on social environment• Theme of multiple interventions.

Supportive policies + community agency + individual engagement

April 2011 32

TimeBirth

Health,

Quality of life

Death

Disability-free survival

The red line represents a survival curve for a population. The blue lines represent varying levels of disability among survivors. Squaring the curve implies shifting these lines up and to the right, towards the

green line, which represents the hypothetical population health limit.

HP Goals: “Squaring the survival curve”

April 2011 33

Health Promotion• Origins in Health Education; limitations of giving info• Social Marketing approach

– How to transmit ideas & attitudes: identify needs; demonstrate advantages; audience segmentation; select channels, etc.

• New approaches based on behavior change theories– Health Belief model– Stages of Change model

• Early Risk reduction strategies• Later Healthy public policy

– Tax policy to promote healthy behaviour– Anti-smoking laws, seatbelt laws– Affordable housing

• Community engagement

April 2011 34

Health Promotion

• Ottawa Charter for Health Promotion (1987)• Five key pillars to action:

– Build Healthy Public Policy

– Create supportive environments

– Strengthen community action

– Develop personal skills

– Re-orient health services

Prerequisites for health = peace, shelter, education, food, income, stable ecosystem, sustainable resources.

April 2011 35

Objective:

• “Identify the potential community social, physical and environmental factors that might promote healthy behaviours, as well as ways to assist communities in addressing these factors.”

• Green’s model:

April 2011 36

Identify the administrative &

financial policies needed

Identify education, skills & ecology

required

Identify desirable outcomes:Behavioural, Environmental, Epidemiological, Social

Predisposing factors

Enabling factors

Reinforcing factors

Lifestyle

Environment

Planning phaseWhat can be achieved? What needs to be changed to achieve it?

What can be learned? What can be adjusted?

Evaluation phaseAdapted from: Green L. http://www.lgreen.net/precede.htm

Policies

Resources

Organisation

Service or programme components

Health status Quality of

life

Implementation:What is the programme intended to be?What is delivered in reality?What are the gaps between what was planned and what is occurring?

Process:Why are there gaps between what was planned and what is occurring?What are the relations between the components of the programme?

Impact:What are the programme’s intended and unintended consequences?What are its positive and negative effects?

Outcome:Did the programme achieve its targets?

Start

Finish

April 2011 37

Public health ethics• Underlying principles of

– Respect for autonomy (dignity & making one’s own choices)

– Beneficence (do good)– Non-maleficence (do more good than harm)– Justice (distribute benefits fairly & impartially)

• Four virtues: Prudence, Compassion, Trustworthiness, Integrity

• Conflicts: – Beneficence for majority may conflict with autonomy,

e.g. in infectious disease control– Justice in funding prevention vs. high-tech cure – Between values in different cultures (e.g. reproduction)

April 2011 38

Ethics topics in MCC exam• Competency (among elderly, and for adolescents)

– Who makes decisions: proxies, living wills, etc.

• Consent to treatment– informed consent; battery

– need for repeat consent for 2nd surgery, etc;

• Withdrawal of care ; assisted suicide• Disclosure: adverse events • Justice • Legal issues: Record keeping

April 2011 39

Some ethical principles in Public HealthSocial beneficence versus individual autonomy:• Isolation & quarantine restrict freedom but are acceptable in communicable

disease control. However, maintain confidentiality & avoid stigma. • Authority to search for contagious cases is acceptable.• Mass medication (beneficence vs. nonmaleficence):

– Harm : benefit ratios for immunizations have to accept some individual harm (should we stop immunization against measles after it is eradicated, thereby risking returning epidemics?) Risks of not immunizing usually greater; everyone must be informed.

– Opposition to fluoridation: political or evidence-based?• Privacy & health statistics (individual autonomy vs. social beneficence)

– Surveillance systems can use anonymous, unlinked data (e.g. from blood test results)

– Subsequent analyses of medical records for research purposes– Computerized record linkage– Issue of research discoveries that damage commercial interests

(e.g. industrial pollution; cigarette companies & lawsuits)• Informed consent is required for testing (e.g. HIV) (autonomy)

– Debate, however, over anonymity vs. linking to allow for counseling.

April 2011 40

• Occupational health code of ethics guides balance between protecting company which employs you and worker. – Put the health of the worker first; must inform workers of health

threats– MD to remain fully informed of the working conditions– Advise management of health threats; workers can inform unions– Apply precautions– Must not reveal commercial secrets, but must protect workers’

health– Only inform management of worker’s fitness to work, not the

diagnosis• “Crimes against the environment” (pollution, etc) conflict

with economic interests & jobs (which harm health also)• Legally subpoenaing research records in order to discredit

the data or pursue legal action (e.g. toxic shock case; breast implant study) not allowed, but variations in ruling.

(Ethical principles, cont’d)

April 2011 41

Population health 78-7 Health of Special Populations Enabling objectivesAboriginal health• Describe the diversity amongst First Nations, Inuit, and/or Métis communities • Describe the connection between historical and current government practices

towards First Nations, Inuit, Métis peoples (including, but not limited to colonization, residential schools, treaties and land claims), and the intergenerational health outcomes that have resulted.

• Describe medical, social and spiritual determinants of health and well-being for First Nations, Inuit, Métis peoples

• Describe the health care services that are delivered to First Nations, Inuit, Métis peoples

Global health and immigration. • Identify the travel histories and exposures in different parts of the world as risk

factors for illness and disease. • Appreciate the challenges faced by new immigrants in accessing health and social

services in Canada. • Appreciate the unique cultural perspective of immigrants with respect to health

and their frequent reliance on alternative health practices. • Discuss the impact of globalization on health and how changes in one part of the

world (e.g. increased rates of drug-resistant Tuberculosis in one country) can affect the provision of health services in Canada.

April 2011 42

(Objectives, continued)Persons with disabilities.. • Identify the challenges of persons with disabilities in accessing health and

social services in Canada. • Discuss the issues of stigma and social challenges of persons with disabilities

in functioning as members of society (link to mental health). • Discuss the unique health and social services available to some persons with

disabilities (e.g. persons with Down’s syndrome) and how these supports can work collaboratively with practicing physicians.

Homeless persons. • Identify the challenges of providing preventive and curative services to

homeless persons. • Discuss the major health risks associated with homelessness as well as the

associated conditions such as mental illness. Challenges at the extremes of the age continuum. • Identify the challenges of providing preventive and curative services to

isolated seniors and children living in poverty. • Discuss the major health risks associated with isolated seniors and children

living in poverty. • Discuss potential solutions to these concerns.

April 2011 43

Aboriginal groups• Know basic demographics: groups; age pyramid; • Elevated rates of

– Trauma, poisoning, SIDS, ALTE (Apparent Life Threatening Event Syndrome)

• also suicide, substance use– Circulatory diseases (incl rheumatic fever)– Neoplasms– Respiratory diseases– Infection (gastroenteritis, otitis media, infectious

hepatitis)– Diabetes

• Inuit population probably most acutely affected.• Questions probably focus on determinants

rather than statistics: list…

April 2011 44

Special populations: Seniors

• Risk of– Musculoskeletal injuries

• includes falls & injuries

– Hypertension/heart diseases– Respiratory diseases– Dementia– Polypharmacy

April 2011 45

Special populations: Children in Poverty

• Note life course approach (above): lasting impact of early deficits– Low birth weight– Trauma/poisoning– Oral problems (abnormalities in teeth and jaws)– Fever/infectious diseases– Psychiatric problems

April 2011 46

Special populations: People with Disabilities

• Increased risk of– Emotional & psychological problems– Job insecurity (hence low income & poverty)

April 2011 47

Some MCQs.

April 2011 48

28) In describing the leading causes of death in Canada, two very different lists emerge, depending on whether proportional mortality rates or person-years of life lost (PYLL) are used. This is because:

a) one measure uses a calendar year and the other a fiscal year to calculate annual experience

b) one measure includes morbidity as well as mortality experience

c) both rates exclude deaths occurring over the age of 70d) different definitions of “cause of death” are usede) one measure gives greater weight to deaths occurring in

younger age groups

April 2011 49

Which of the following statements concerning cross-cultural care is true?

a) It has proven very hard to change physicians’ attitudes and make them more culturally aware.

b) There still is no formal accreditation requirement to train physicians in cross-cultural skills.

c) There is considerable literature comparing the effectiveness of different techniques of cross-cultural communication

d) Lower quality care results when clinicians fail to acknowledge cultural differences.

e) The CMA and Royal College have collaborated to produce clear guidelines on developing cultural competency.

April 2011 50

26) All of the following statements are true EXCEPT:

a) one indirect measure of a population’s health status is the percentage of low birth weight neonates

b) accidents are the largest cause of potential years of life lost for men in Canada

c) the Canadian population is steadily undergoing rectangularization of mortality

d) morbidity is defined as all health outcomes excluding death

e) the neonatal mortality rate is the number of infant deaths divided by the number of live births multiplied by 1000

April 2011 51

Which of the following statements about oral health is true?

a) Children with cleft lip or palate are at increased risk of otitis media.

b) Dental caries may affect a child’s growthand development.

c) d) e) All of the above

April 2011 52

44) Of the five items listed below, the one which provides the strongest evidence for causality in an observed association between exposure and disease is:a) a large attributable risk

b) a large relative risk

c) a small p-value

d) a positive result from a cohort study

e) a case report

April 2011 53

Which of the following test characteristics are typical of a screening test?

A. High sensitivity and high specificity.

B. High sensitivity and low specificity.

C. Low sensitivity and high specificity.

D. Low sensitivity and low specificity.

E. Low sensitivity and low accuracy.

April 2011 54

23) Which of the following is the most important justification for mounting a population screening program for a specific disease?a) early detection of the disease of interest is

achieved

b) the specificity of the screening test is high

c) the natural history of the disease is favorably altered by early detection

d) effective treatment is available

e) the screening technology is available

April 2011 55

40) The effectiveness of a preventative measure is assessed in terms of:a) the effect in people to whom the measure is

offered

b) the effect in people who comply with the measure

c) availability and the optimal use of resources

d) the cost in dollars versus the benefits in improved health status

e) all of the above

April 2011 56

42) Each of the following is an example of primary prevention EXCEPT:a) genetic counselling of parents with one retarded

child

b) nutritional supplements in pregnancy

c) immunization against tetanus

d) chemoprophylaxis in a recent tuberculin converter

e) speed limits on highways

April 2011 57

12) The following indicate the results of screening test “Q” in screening for disease “Z”:

The specificity of test “Q” would be:a) 40 / 70b) 120 / 130c) 40 / 50d) 120 / 150e) 40 / 130

April 2011 58

13) The positive predictive value would be:a) 40/70b) 120/130c) 40/50d) 120/150e) 70/200

April 2011 59

43) Which of the following describes the factors in the classic “epidemiological triad” of disease causation? a) host, reservoir, environment

b) host, vector, environment

c) reservoir, agent, vector

d) host, agent, environment

e) host, age, environment

April 2011 60

23) Which of the following is the most important justification for population screening programs for a specific disease?a) early detection of the disease of interest is

achieved

b) the specificity of the screening test is high

c) the natural history of the disease is favourably altered by early detection

d) effective treatment is available

e) the screening technology is available

April 2011 61

42) Each of the following is an example of primary prevention EXCEPT:a) genetic counselling of parents with one retarded

child

b) nutritional supplements in pregnancy

c) immunization against tetanus

d) chemoprophylaxis in a recent tuberculin converter

e) speed limits on highways

April 2011 62

More MCQs

• Here are some more questions that students can use to test their own knowledge:

http://www.medicine.uottawa.ca/sim/data/Self-test_Qs_Pop_Interventions_e.htm

• (The questions contain comments on the answers, to illustrate why a given response is not correct)

April 2011 63

Ten leading causes of death, Canada, 2006 (sexes combined, all ages)

Ten leading causes of death, Canada, 2006 (sexes combined, all ages)

0 10 20 30 40

Malignant neoplasms 29.7%

Diseases of the heart 21.9%

Cerebrovascular diseases 6.1%

Chronic lower respiratory diseases 4.3%

Unintentional injuries (accidents) 4.2%

Diabetes mellitus 3.2%

Alzheimer’s disease 2.5%

Influenza & pneumonia 2.3%

Nephritis, nephrotic syndrome & nephrosis 1.6%

Suicides 1.5%

Source: Statistics Canada, http://www.statcan.gc.ca/pub/84-215-x/2010000/tbl/t001-eng.pdf

Percentageof all deaths