PH011

The Natural History of a Disease (Diagram)

PH011

Health Protection (Defn)

PH011

Disease Prevention, Health Protection and Health Prevention: Lung Cancer Example (Diagram)

PH011

Methods of primary prevention (5)

PH011

Incubation period (infectious disease)

vs

Latent period (non-infectious disease)

Latent Period:
      Interval between exposure and manifestations of a disease

PH011

Pre-clinical detectable phase (Def'n)

Pre-clinical phase (Def'n)

Pre-clinical detectable phase

Later part of the pre-clinical phase (incubation period or latent period) during which it is possible to detect a disease prior to the onset of symptoms

Pre-clinical phase

Same as incubation period or latent period

PH011

Case-Fatality Rate (ex calc)

PH011

Haddon’s Matrix

PH030

Describe the 3 factors in medical decision making that define evidence-based medicine

1. Clinical expertise:

Clinician’s cumulated experience, education and clinical skills

2. Patient values and preferences:

Patient brings to the encounter his/her own personal and unique concerns, expectations, and values

3. Best research evidence:

Clinically revelant research that has been conducted using sound methods

PH030

PICO

P = Patient or problem

Most important characteristics of patient, including the primary problem, disease, or co-existing conditions and may include sex, age, or race

I = Intervention, prognostic factor, or exposure

What you want to do for the patient (ex. prescribe a drug, order a test, order surgery), what factors may influence outcome for patient (ex. age, co-existing problems, exposures)

C = Comparison

Main alternative to compare with the intervention (ex. choosing between two drugs, diagnostic tests), you do not always need a comparison

O = Outcomes

What you hope to accomplish through the intervention (ex. relieve or eliminate symptoms, reduce adverse effects, or improve functioning)

PH030

Describe the process of how to find the best evidence that answers the question

Type of Question - Suggested best type of study

Select a resource and conduct a search

Type of Question - Suggested best type of study
Diagnosis  - Prospective, blind comparison to a gold standard

Therapy  -  RCT > cohort > case control > case series

Prognosis  - cohort > case control > case series

Harm/Etiology - RCT > cohort > case control > case series

Prevention - RCT > cohort > case control > case series

Clinical - Exam Prospective, blind comparison to gold standard

Cost Benefit - Economic analysis

PH003

International Classification of Impairments, Disabilities and Handicaps (ICIDH) Definitions

Impairment

Disability

 Handicap

Impairment:

"Any loss or abnormality of psychological, physiological or anatomical structure or function" (e.g. blindness)

Disability:

"Any restriction of lack of ability to perform an activity in a manner or within the range considered normal for a human being." (e.g. inability to drive a car because of blindness)

Handicap:

"The disadvantage for a given individual, arising out of impairment and disability, that limits or prevents the fulfillment of a role that is normal (depending on age, sex and social and cultural factors) for that individual as determined by society." (e.g. inability of a taxi driver to continue to earn a living because of blindness)

PH003

 Overview of ICF Definitions
(International Classification of Functioning, Disability and Health)

1. Body functions

2. Body structures

3. Impairments

4. Activity

5. Participation

6. Activity limitations

7. Participation restrictions

8. Environmental factors

This classification system uses more positive terminology than ICIDH

e.g. participation instead of handicap, activity rather than disability

Also impairments, activity limitations and participation restrictions are described and measured by degree, rather than in absolute terms, and emphasizes that is a person is not, in an all-or-nothing way, “disabled” or “not disabled”, “handicapped” or “not handicapped”. 

1. Body functions are the physiological functions of body systems (including psychological functions).

2. Body structures are anatomical parts of the body such as organs, limbs and their components.

3. Impairments are problems in body function or structure such as a significant deviation or loss.

4. Activity is the execution of a task or action by an individual.

5. Participation is involvement in a life situation.

6. Activity limitations are difficulties an individual may have in executing activities.

7. Participation restrictions are problems an individual may experience in involvement in life situations.

8. Environmental factors make up the physical, social, and attitudinal environment in which people live and conduct their lives.

PH003

Define the Three Elements of an Epidemiologic Rate

Numerator (part of denominator)

Denominator

Time period (or point)

PH003

Mortality rates

1. Crude mortality rate

2. Cause-specific mortality rate

3. Infant mortality rate

4. Proportional mortality

5. Case-fatality rate

Crude mortality rate:

"The number of deaths reported in a given population over a specified period of time - usually one year - divided by the total population"

Cause-specific mortality rate:

This is the rate of death for a specific disease (e.g. lung cancer) or a group of diseases (e.g. all cancers). The numerator is the number of deaths due to that cause; the denominator is the total population at risk to get the specific disease.

Infant mortality rate:

Rate of death of infants (children in their first year of life); numerator = deaths of children before their first birthday, denominator =  all live births per year.

Proportional mortality:

This is the proportion of all deaths in a given population, which are due to a specific cause. Numerator is the number of deaths due to that cause; the denominator is the total number of all deaths of any cause.

Case-fatality rate:

The proportion of cases of a specified condition which are fatal within a specified time.  Numerator is the number of deaths from a disease (in a given period).  Denominator is the number of diagnosed cases of that disease (in the same period). E.g. if one in ten cases of meningococcal meningitis die, the case-fatality rate is 10%. If there is no time frame, then technically it would be more correct to call it a case-fatality proportion; i.e. the proportion of diagnosed cases that die from that disease (at any time or rate).

PH066

Roles of a physician (7)

1. Medical Expert Role (examinable info)

Combat overproduction

PH066

Which is true?

1.Hospital Insurance and Diagnostic Services Act passed in 1957

 2.Medical Care Act passed in 1968

 3.Canada Health Act passed in 1984

 4.All of the above

 5.None of the above

Which of the following is not a Federal Responsibility in Health?

All of the above

Cancer Drugs

PH066

Medical Care Act (Medicare)

- National Medicare program

- Extended cost sharing with provinces for all “medically necessary” physician services

- Could include other services at provincial discretion

- Federal government pays 50% of costs, provinces pay the balance

- Provinces must meet terms and conditions:

Comprehensive coverage

Universality

Portability

Public administration

PH066

Canada Health Act

  (1984)

- Replaces Hospital Insurance and Diagnostic Services Act (1957) & Medical Care Act (1966)

- Prevent regional variation in services

- Attempts to influence delivery of health care

- Bans extra-billing by physicians

- Allows Ottawa to withhold funds from provinces who don’t comply with the Act’s 5 principles

a.       Public administration

                                                     i.   Not for profit, carried out by a public agency

                                                   ii.   Financially accountable to the provincial government

b.   Comprehensiveness

                                                     i.   Program must cover all medically necessary hospital and medical services, as well as surgical-dental services rendered in hospital

c.    Universality

                                                     i.   All eligible residents must have access to public healthcare insurance and insured services on uniform terms and conditions

d.   Portability

                                                     i.   Benefits are portable when temporarily absent from province

e.    Accessibility (New addition!)

                                                     i.   Must provide insured services on uniform terms and condition – no discrimination

PH066

Describe the structure of government and enabling legislation applicable to the health system in Canada

A. Health care falls under provincial jurisdiction, with funding coming mostly from the federal government. Has primary responsibility for:

Health care

Education

Regulating professionals

Managing the system

Areas not included under Canada Health Act (e.g. public health, home care, outpatient medications)

Finances hospitals, physicians, other health care workers, drug plans for seniors and those on public assistance

Local / regional bodies

Provide services as delegated by provincial government

Most provinces experimenting with regional models (e.g. Regional Health Authorities)

Eliminates local boards for individual organizations

Assigns responsibility for management and resource allocation to regional level

Provinces vary widely as to how regions are set up, what they are responsible for and what powers they are given

B.  BNA act – really set the idea of health care under provincial jurisdiction

C. Canada Health Act (1984)

PH066

Non Government Health Services

Non for profit

Regional health authorities

Hospitals, personal care homes

Volunteer agencies

For profit

Home care, personal care homes

Private

Medical care (e.g. elective plastic surgery) optometry, dental, chiropractic, drug plan

PH066

Explain the difference between the undifferentiated physician, the general practitioner, the family medicine specialist, and the Royal College specialist

A.General practitioner is no longer available, family medicine specialist is the new division (generalist specialist, CCFP)

B.61 specialties under Royal College specialist category (FRCPSC)

PH066

The five bases for division of labour amongst the medical profession

1. Generalist vs. specialist

2. Physical vs. mental

3. Diagnostic vs. treatment

4. Individual vs. population

5. Research/teaching/administrative/practice

PH013

Primary Prevention (2 Approaches)

1. Reducing exposure

- Environmental risks

- Occupational

- Sanitation   

- Active or passive

Safe drinking water and sanitation (passive) using protective gear (active)

2. Reducing susceptibility

Modifying the susceptibility of the body to biological agents

           Active or passive

Examples: Immunization (passive), brushing and flossing (active) wearing seatbelt, choosing not to smoke

PH013

Define secondary prevention and give three example of the physician’s role

a.    Secondary prevention – detection and early treatment of disease

b.   Three examples of Physicians Role

                                                     i.   Patient education regarding screening

                                                   ii.   Case finding

                                                 iii.   Self care education

PH013

Screening vs Case Finding

Screening:

“Tests done on apparently well people to identify those at an increased risk of a disease or disorder”

Leads to early diagnosis before symptoms begin

Case Finding:

Looking for additional illnesses in those with medical problems, but not symptoms related to the condition sought

Examples: Checking blood pressure in a diabetic patient, cervical swabs during PHE, pregnancy induced diabetes 

PH013

List and explain the five disease requirements which must be met to justify the use of a screening test

1. Important health problem

2. Natural history must be understood

3. High prevalence

4. Effective treatment is available

5. Early treatment is more effective than treatment after the development of symptoms

PH013

List and explain five important characteristics of a good screening test (6)

1. Inexpensive

2. Safe

3. Acceptable to population

4. Quick and easy to administer

5. Valid and reliable

6. Defined cutoff level

PH013

The Screening Cascade

a.         Screening process (sieve)

b.         Investigation of detected abnormalities (sort)

c.         Treatment of identified condition (intervene)

PH013

The Popularity Paradox

The greater the harm through overdiagnosis and overtreatment from screening, the more people there are who believe they owe their health, or even their life, to the program

PH013

Potential Harms of Screening

Level 1:

Physical: pain, organ damage nerve injury
Psychological and social: Anxiety, excessive awareness of health

Level2:

Pain, scaring, infection from biopsy,  Anxiety induced by positive results, false reassurance from false neg results.

Level 3:

Adverse drug effects (lipids), impotence, incontinence, death from prostatectomy

PH013

Biases in screening

Volunteer bias:
Healthy individuals more likely to attend screening programs resulting in over-screening of low risk people and under-screening high risk population

e.g. Pap tests: First nations and immigrant women less likely to attend but have higher rates of cervical cancer

Lead-time bias:
Death occurs at same time regardless of screening. Diagnosis is however made earlier due to screening, therefore patient lives longer with knowledge of the diagnosis but does not live longer overall

e.g. lung cancer

Length time bias:
Slowly progressing disease has longer pre-clinical phase, therefore more likely to be detected; and longer survival regardless of early detection

e.g. different types of breast cancer or prostate cancer

PH019 - PSA

Prostrate-specific-antigen (PSA) test

Review articles (Sept 9 assigned study)

PH022

Criteria for usefullness of a Diagnostic Test

Accessible

Affordable

Acceptable

Valid: sensitivity, specificity, positive predictive value, negative predictive value

Reliable: Repeatability

PH022

To use any diagnostic test properly, you need to know three things:

1. Sensitivity (of test)
   
   
2. Specificity (of test)
   
   
3. Prevalence (of disease) = Pre-Test Probability
   Proportion of people in the population with the target disorder at a specific time (point prevalence) or time interval (period prevalence)

PH022

Calculating Sensitivity and Specificty

Sensitivity = TP/All sick (SNNOUT)

Specificity = TN/All not sick (SPPIN)

PH022

PPV

[image]

PH022

NPV

PH022

PPV and NPV are...

Dynamic

They change with a change in the prevalence of disease in the population examined
Incorporate:
    Sens
    Spec
    Prev
Much more useful for clinical practice

PH022

Receiver Operator Characteristic (ROC) Curve

• Illustrates relationship between sensitivity and specificity
• Line graph that plots the probability of a true positive result (sensitivity) against the probability of a false positive result for a range of different cut-off points
• Used to help assess the usefulness of the test and to determine the most appropriate cut-off points
• Most convex part is the best tradeoff between sensitivity and specificity
  
  

PH022

As prevalence of a disease increases...

Is “Accuracy” A Better Term?

PPV increases and NPV decreases

[image]

PH022

Likelihood Ratios

[image]

LR+=Ratio of TP / FP
LR- = Ratio of FN/TN

PH022

Principal decisions that determine rational medical treatment of any patient

1. Treatment must be appropriate to the setting
   
   
2. Balance of benefits and harms to the patient from therapy must be considered
   
   
3. Patient’s values and expectations for outcome must be known and incorporated
   
   
4. Shared decision making

PH020 - Tutorial on Stats

PH023 - Tutorial on LR Stats

Do these after studying Q cards

PH015

  Describe the main historical developments in the understanding of the causes of disease.

1. Biomechanical/biomedical model (17th C): mind & body separate entities
2. Germ theory of disease (end of 19th C): diseases where caused by a transmissible agent
3. Epidemiological triangle: agent, host, environment (20th C)
4. Web of Causation (20th C): Builds on Epidemiological triangles stating that many factors contribute to disease
5. Theory of general susceptibility (late 20th C): ability to handle whole range of different aspects of life leads to overall good health ie. good outlook on life helps lower susceptibility

PH015

Name the 4 elements of the Health Field Concept

1. Human Biology
2. Environment
3. Lifestyle
4. Health Care System

PH015

Explain “health promotion”

Health promotion: influencing healthy behaviour and social & environmental conditions that influence such behaviour. This involves enabling people to increase control over their health.
The Ottawa Charter involved five main components:

1. Reorienting health services

2. Enhancing personal skills

3. Strengthening community action

4. Creating supportive environments

5. Building healthy public policy

PH015

List the “prerequisites of health” of the 1986 Ottawa Charter (8)

Prerequisites of Health: PSEFI - SSS

Peace

Shelter

Education

Food

Income

Stable ecosystem

Sustainable resources

Social justice & equity

PH015

12 determinants of health

Income & Social Status
ex. therapy, dieticians,

Social Support Network
Ex. If peer & parents do not smoke individuals are less likely to smoke

Education

Ex. Health living course in educational systems

Employment & Working Conditions
Individuals w/ better control over working conditions & less stressful job are healthier.

Ex. Dangerous working Env.

Physical Environment
One’s natural surrounding
Ex. Water, air quality, housing, roads,

Biology & Genetic endowment

Personal health practices & coping skills
Psychological characteristics enables & supports healthy choices & help deal with stress/life

Ex. Exercising, relaxation techniques, binge drinking

Health Child development
Prenatal & early childhood experiences on health

Ex. Fetal alcohol syndrome, Spinobifita

Health & social services
Access to services designed to promote health & prevent disease

Gender
Biological diff. in sex & socially constructed genders

Ex. Gender specific diseases

Culture
Ex Cultural cuisines

Social environment
Organization, Relationships and connections

PH015

Name 3 priorities for action recommended by the “Second Report on the Health of Canadians” in addressing current & future challenges to health in Canada

1. Renewing & Reorienting the health sector with main focus on health promotion
2. Investing in the health & well-being of key population groups in particular children, youth & Aboriginal people.
3. Improving in health by reducing inequities in literacy, education & distribution of incomes in Canada.

PH008

Algorithm for classification of types of clinical
research

PH010

CCSVI

Stands for chronic cerebrospinal venous insufficiency - Possible diagnosis at etiological cause of what is classified as MS.

Surgery is done where Paolo Zamboni theorized that blood trying to get to the heart was blocked in neck. It backed up, leaving iron deposits in the brain, which in turn led to the lesions on nerves that epitomize
multiple sclerosis. And he found that a relatively simple
procedure of threading the blocked vein with a balloon, much like angioplasty in arteries, would ease symptoms for many MS patients. He called it "liberation."

PH018

What three demographic rates determine the size and shape of the pyramid?

1. Birth Rate
   
   
2. Death Rate
   
   
3. Migration Rate

PH026

List the 5 E’s of evaluating health interventions

1. Epidemiology
   Diagnosis
   Prognosis (describe the natural history of disease and probable outcomes under various treatment strategies)
   Treatment
2. Efficacy
3. Effectiveness
4. Efficiency
5. Ethics

PH026

Define efficacy and give an example of an efficacy study

• Efficacy - The net benefit of an intervention under IDEAL conditions, best measured during a controlled trial using state of the art methods.
  
  
• It does not take into account the practical issues of application in a clinical setting.
  
  
• Measuring efficacy requires a method of high validity (like randomized controlled trial (RCT) or meta-analysis (like Cochrane Collaboration) and cannot be inferred from expert opinion or observational studies.
• An example is a RCT of the effect of a new drug on a particular set of patients.

PH026

Effectiveness

Effectiveness is a measure of how well an intervention works under real local conditions, which depends on both the efficacy of the intervention and the extent to which it can be implemented appropriately.

Therefore, the effectiveness of an intervention is almost always less impressive than its efficacy. If there are two interventions of similar efficacy, the one which can be more fully implemented in practice will have a higher effectiveness.

Examples of factors that can reduce the effectiveness of an intervention are:
•    Lack of uptake by physicians
•    Poor compliance by patients
•    Poor availability or access to the intervention or treatment
•    Absence of skills or technology

PH026

How can you distinguish between an efficacy and an

effectiveness study?

• RCTs and meta-analyses of RCTs are always efficacy studies
• Efficiency studies take many forms but rarely RCTs
• Real-world settings
• Observational methodology (correlations)

PH026

Efficiency takes into consideation...(3)

List four types of efficiency measures

Efficiency takes costs into consideration:

• Direct Costs
• These are the costs of transactions and materials that are directly attributable to the intervention provided. Examples of direct costs include MD fees, nursing costs, drugs....
• Indirect Costs
• These are the costs that occur due to the loss of life, productivity or livelihood. For example, a treatment that allows an individual to recover to the point where they can resume their previous employment has lower indirect costs than a treatment that saves a life, but doesn’t allow the individual to return to work.
• Intangible costs
• These are the costs of pain, suffering, grief and other non-financial costs of disease and medical care

PH026

List four types of efficiency measures

4 types of efficiency studies:

1. Cost-minimization - Appropriate when the outcome is the same but there are several ways to get to it. Find the cheapest way.
2. Cost-effectiveness - Appropriate when have two potential treatment for the same condition. One is more effective but costs more. Is the extra effectiveness worth the extra cost?
3. Cost-utility - Cost per QALY (quality-adjusted life year). Takes into account quantities and quality of life.
4. Cost-benefit - Puts everything in terms of dollars.

PH026

Decision Analysis and its 4 steps

Only useful when

Decision Analysis - a method of bringing together information from a variety of sources to improve clinical outcomes. It is used for both individual patients with their physicians to organize information to make a decision about the treatment as well as for structuring and analyzing collective decisions such as programme evaluation and economic appraisal.

Four steps:
i.    Identify the problem
ii.     Diagram the options
iii.     Obtain information for each option
iv.    Compare the values and perform sensitivity analysis

Decision analysis is only useful when:
-    There are real decisions to be made
-    The outcomes are not immediately obvious
-    There is good information in the literature
What is intuitively obvious is not always correct.

PH005

Statistical associations vs. Causal relationships

Statistical association (relationship):
Statistical dependence between two events, characteristics or other variables

Positive associations: two events or variables tend to occur together, e.g., aging and gray hair

Negative associations: when one event occurs, the other does not, e.g., aging and breaking Olympic records in swimming.

Causal relationships: cause and effect relationship
Three alternative explanations to explain causality:

• Chance
• Bias
• Confounding

PH005

Case-Control studies

Compare those diseased (cases) with those not diseased (controls), then look for previous exposures

Best way to look at rare diseases or those with long interval between exposure and disease
Makes optimal use of the most informative individuals, can be done more quickly and require fewer subjects than cohort studies

Statistic employed is “odds ratio”
H₀ = OR = 1
H_A = OR differs from 1 significantly

PH005

Cohort Studies

Define subsets of a population based on exposure

Follow forward in time, observe outcome and after sufficient time compare the populations with regard to the outcome of interest.

Use a Risk Ratio or Rate Ratio (depending on info given)

PH005

Types of measuring statistical association

We use statistical measures collectively known as relative risks including:

Risk ratio = Risk in the exposed group ÷ Risk in the unexposed group (Cohort, Clinical Trials)
Rate ratio = Rate in the exposed group ÷ Rate in the unexposed group (Cohort, Clinical Trials)
Odds ratio = Odds in the exposed group ÷ Odds in the unexposed group (Case - Control)

PH005

 Selection biases and Information biases

Selection biases
     Length (prevalence-incidence) bias
     Responder bias (volunteer bias)
     Lead-time bias (screening bias)
     Berkson’s bias

Information biases
     Recall bias
     Measurement bias

PH005

Control Confounding by...(3)

• Randomization (only in clinical trials)
  
  
• Exclude people who have the confounding factor (“restriction”)
  
  
• Stratified analysis

PH005

Koch’s (Koch-Henle) Postulates (1880)

1. Agent must be present in every case of the disease (necessary)
2. Agent should occur in no other disease (specific)
3. Agent must be isolated from body of diseased, grown in pure culture, and when introduced into another animal/person, produces the disease (sufficient)
4. Used for infectious diseases. Not useful for chronic diseases

PH005

Bradford-Hill Criteria (9)

1. Experimental evidence - Does the experimental addition of the putative causal factor increase the incidence of the disease when all other factors are controlled for? Better if done with Humans
   
   
2. Consistency of the association - Do the findings of studies of the same and different design in different populations demonstrate the same association?
   
   
3. Strength of the association - How big is RR?
   
   
4. Dose-response or biological gradient
   
   
5. Temporal relationship - exposure occurs before disease
   
   
6. Plausibility - Biological mechanism known?
   
   
7. Coherence – does the cause make sense with other current knowledge?
   
   
8. Specificity – is the association specific for a given disease or a subtype of a disease?
   
   
9. Analogy – do other established associations provide a model for this relationship?

PH005

Define, calculate, and interpret concepts of:

Absolute risk difference

Relative risk

Odds ratio

Attributable risk percent in the exposed

Population attributable risk

Absolute risk difference – difference of risk between two groups

= R1 – R2

Relative risk – ratio of absolute risk in one group compared to another;

= R1 / R2

Odds ratio – relative odds between two groups (e.g. chance of you developing a disease if you were exposed was 10 times higher than if you weren’t; alternatively, you were 10 times more likely to develop the disease if you were exposed)

Attributable risk percent - This represents the proportion of cases among those exposed to a risk factor that was attributable to that risk factor. It is calculated as
= (Risk of Disease in Exposed group - Risk of disease in unexposed group)/Risk of disease in Exposed group

Population attributable risk - this is the proportion of cases in the whole population (exposed and unexposed) that is attributed to exposure to a risk factor. It is calculated as:

= (Risk of disease in the whole population - Risk in unexposed group)/Risk of disease in the whole population

PH009 - Tutorial Qs on OR, RR etc.

PH016

What percentage of patients who present to their family physician are experiencing stress-related symptoms?
a.20%
b.40%
c.60%
d.80%
e.95%

PH016

Describe the field of psychoneuroimmunology and its role in understanding stress.

The field of psychoneuroimmunology (PNI) is the study of the interaction of stress, the immune system, and health outcomes.

Research of PNI has lead to discoveries of a direct link between stress and the immune system. For example, during exams, stress leads to increased susceptibility to viral infection.

PH016

What is stress?

A threat to homeostasis

When demands of environment > capacity to adapt

– internal and/or external
–physical and/or psychological

PH016

General Adaptation Syndrome: Hans Selye