Population Health

Question 1

Main reason for increased life expectancy in Canadians

Answer 1

Decreased infant mortality rate

Question 2

Lead time bias

Answer 2

Overestimate the survival time from dx b/c screening at occult stage of dz vs dx at later stage

Question 3

Length time bias

Answer 3

Overestimate the survival time due to screening at one point including more stable cases than aggressive cases, who may have shorter survival times

Question 4

Screening test must have high sensitivity or specificity?

Answer 4

High sensitivity

Question 5

Incidence

Answer 5

# new cases in a time interval / persons at risk in time interval
Measures rate of new infections

Question 6

Prevalence

Answer 6

# existing cases at a point in time / persons at risk at that time 
Measures frequency of disease at a point in time

Question 7

Top 5 causes of mortality in women in Canada

Answer 7

Cancer
Heart disease 
Stroke 
Chronic lower respiratory dz 
Accidents

Question 8

Top 5 causes of mortality in men in Canda

Answer 8

Cancer
Heart disease 
Accidents 
Chronic lower respiratory dz 
Stroke

Question 9

Specific test

Answer 9

Use to rule IN a hypothesis

Very few false positives

Question 10

Sensitive test

Answer 10

Use to rule OUT a hypothesis

Very few false negatives

Question 11

Likelihood Ratio definition

Answer 11

Likelihood that a given test result would be expected in a pt with disease compared with likelihood that same result would be expected in pt without disease

Question 12

Likelihood ratio + equaiton

Answer 12

Sensitivity / (1- specificity) = (TP / (TP + FN)) / (FP/(TN+FP)
How much the probability of a disease increases if the test is positive

Question 13

Likelihood ratio - equation

Answer 13

(1-sensitivity)/specificity = (FN/(TP+FN)) / (TN/(TN+FP))

How much the probability of disease decreases if the test is negative

Question 14

Positive predictive value

Answer 14

Proportion of ppl with +ve test who have the disease

PPV = TP / (TP + FP)

Question 15

Negative predictive value

Answer 15

Proportion of ppl with -ve test who don’t have the disease

NPV = TN / (TN + FN)

Question 16

Sensitivity

Answer 16

Proportion of ppl with disease who have a +ve test

Question 17

Specificity

Answer 17

Proportion of ppl without disease who have a -ve test

Question 18

Sensitivity/specificity are characteristics of the test or prevalence of the disease?

Answer 18

Test

Question 19

Likelihood ratio depends on the test or prevalence of the disease?

Answer 19

Test

Question 20

PPV and NPV depend on the test or prevalence of the disease?

Answer 20

Prevalence

Question 21

Pretest probability

Answer 21

Probability particular pt has given disease before test/assessment results are known

Question 22

Posttest probability

Answer 22

Revision of probability of dz after pt has been interviewed/examined/tested

Question 23

Odds Ratio eq

Answer 23

(A/C) / (B/D)

Ratio of the odds in favour of disease among the exposed to odds in favour of no disease among the exposed

Question 24

Relative risk

Answer 24

(A/(A+B) / (C/ C+D)

Ratio of risk of a disease among exposed to risk among unexposed

Question 25

Attributable risk

Answer 25

Rate of health outcome in exposed individuals that can be attributed to exposure

Question 26

PICO

Answer 26

Population Intervention Comparison Group or Control Group Outcome that you are trying to prevent or achieve

Question 27

P-value

Answer 27

Denotes the probability that the error of declaring an observed difference to be real rather than by chance P<0.05

Question 28

Power

Answer 28

Probabilty of a true positive result

Question 29

95% confidence interval means

Answer 29

If this test were repeated 100 times, 95 times the result would fall within the interval

Question 30

Level 1 evidence

Answer 30

Based on RCTs big enough to have low risk of incorporating FP or FN results

Question 31

Level II evidence

Answer 31

Based on RCTs too small to provide level I evidence

Question 32

Level III evidence

Answer 32

Based on non-randomized, controlled or cohort studies

Question 33

Level IV evidence

Answer 33

Based on opinion of respected authorities or expert committees

Question 34

Level V evidence

Answer 34

Opinions of individuals who have written/reviewed the guidelines based on experience/knowledge

Question 35

Common diseases spread by contact

Answer 35

Impetigo Chicken pox Warts

Question 36

Common diseases spread by airborne

Answer 36

TB

Question 37

Common diseases spread by droplet

Answer 37

Influenza Mumps Pneumonia

Question 38

10 step approach to control an outbreak

Answer 38

1. Identify the team (local public health units) 2. Establish existence of an outbreak 3. Verify dx (obain medical records) 4. Define a case (Person, place, time) 5. Find cases systemically and create a line listing 6. Perform descriptive epidemiology and develop hypotheses 7. Evaluate hypotheses and conduct additional studies as needed (case-control or cohort studies) 8. Implement control measures (can occur at any stage in outbreak) 9. Communicate findings 10. Continue surveillance

Question 39

Risk assessment for environmental exposures

Answer 39

HIRA Hazard Identification Risk characterization Exposure Assessment

Question 40

Contaminants in water

Answer 40

``` E. coli Salmonella Pseudomonas Shigella Giadia (protozoa) Cryptosporidium (protozoa) ```

Question 41

Contaminants in soil

Answer 41

Tetanus | Pseudomonas

Question 42

Common reportable diseases

Answer 42

``` AIDS Botulism Campylobacter enteritits Chancroid Chickenpox CHlamydia Cholera CDiff Creutzfelt-Jakob Crypospoidiosis, cyclosporiasis Diphtheria Encephalitis (even if viral) Food poisoning all causes Gastroenteritis institutional Gonorrhea H. influenza b invasive Ebola Hepatitis Legionellosis Listeriosis Lym disease malaria Measles Meningitis Meningococcal Mumps Pertussis Pneumococcal invasive Polio Rabies Rubella Salmonellosis SARS Shigellosis Smallpox Strep invasive Syphilis Tetanus TB Typhoid West nile, yellow fever ```