EBM/Research/Ethics

Question 1

2x2 table - Which values change with a chance in disease prevalence?

Answer 1

PPV and NPV

Question 2

What is type 1 vs type 2 error?

Answer 2

Type 1 = false positive study

Type 2 = false negative study

Question 3

Efficacy vs. Effectiveness?

Answer 3

Efficacy: value of intervention to group who accept advice and comply with it (ideal world, theoretical impact)

Effectiveness: value of intervention to a group offered it (real world, actual impact)

Question 4

Define and provide the formula for:

a. Prevalence

b. Incidence

Answer 4

Incidence rate = # of new cases during specific time period / observed person-time among people at risk during this time period

PREVALENCE = # of cases at specific time (new + ongoing cases) / total # of people at specific time
- aka: ‘burden of disease’

Question 5

Define regression analysis and name 2 types

Answer 5

Regression analysis is a set of statistical processes used to define the relationship among variables. It examines the influence of an independent variable on the dependent variable.

Types: Linear regression, Logistic regression

Question 6

5 literature “quality” categories

Answer 6

Level of evidence:
1 - RCT/ systematic review
2- cohort (prospective)
3- retrospective, case-control
4- case series
5- case report, expert opinion

Question 7

4 quality indicators in an RCT

Answer 7

1. Randomization
2. Allocation Concealment
3. Blinding
4. Intention to treat analysis
5. Inclusion and Exclusion Criteria
6. Sample Size Calculation
7. Loss to follow up - patient flow diagram

Question 8

What is the name of the value you calculate in a case-control study that tells you the impact of an exposure on a population?

Answer 8

Odds ratio

Question 9

What four steps are there in creating a clinical decision rule?

Answer 9

derivation, validation, implementation and impact analysis

Question 10

What are the characteristics of a good screening test? A good confirmatory test?

Answer 10

● Highly sensitive
● Sensitive in early disease when subsequent course can be altered
● Acceptable to the population
● Diagnostic test: Highly specific

Question 11

What are 3 requirements for a minor to give consent?

Answer 11

• informed
• non-coerced
• capacity

they “CAN” give consent - capable, appropriate info and non-coercive (voluntary)

Question 12

parents refuse treatment - list 5 steps to address their concerns

Answer 12

1. Identify their concerns
2. Review the importance of the treatment and benefits/risks of treatment
3. Provide alternatives if they exist
4. Use common language/no medical jargon
5. Keep in mind cultural differences and language barriers; may need to include people from their culture that they respect and would like present or to be part of the decision
6. Determine if the child has the capacity to consent to treatment
7. Document all discussions

Question 13

Four ethical principles of human research

Answer 13

• autonomy
• beneficience
• nonmaleficience
• distributive justice
• respect for informed consent
• respect for privacy and confidentiality

Question 14

Three criteria for determining authorship on a scientific paper

Answer 14

● Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AND
● Drafting the work or revising it critically for important intellectual content; AND
● Final approval of the version to be published; AND
● Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Question 15

3 indications to break confidentiality

Answer 15

1. Intended harm to self (i.e. suicidal ideation)
2. Intended harm to others (i.e. homicidal ideation)
3. If there is suspicion of child abuse

Question 16

What are 4 things to do if you have had a medical error?

Answer 16

● medical error disclosure involves explaining what happened and why
● what will be done to prevent recurrence
● offering an apology
● Filing safety report
● Ensuring safety of child

Question 17

What is the age of consent?

Answer 17

16 yo
18 for exploitative
Close in age exception: 12-13yo + 2 years old, 14-15 yo + 5 years old

Question 18

What is intention to treat analysis?

Answer 18

• analysis based on the initial treatment assignment groups (even if that’s not the group they stayed in) and not on the treatment eventually received

vs. per protocol analysis

Question 19

RCT’s - pros and cons

Answer 19

PROS:
o randomization gives best evidence for causality
o minimizes effects of confounders through randomization and blinding
o decreases bias
o efficacy/effectiveness of intervention can be assessed

CONS:
o expensive
o time consuming (long, follow-up required)
o difficult for rare events
o may be unethical
o “volunteer” bias
o narrow inclusion/exclusion criteria can limit generalizability

Question 20

Cohort study - pros and cons

Answer 20

PROS:
o treatment not withheld
o can match subjects for potential confounders
o if prospective, can standardize eligibility and outcome measures
o can study incidence and time course of disease (natural history)
o generally cheaper than RCTs
o can estimate relative risk (incidence)

CONS:
o controls may be difficult to obtain (researchers aren’t in control of what the exposure is/was)
o does not deal with unanticipated confounders
o challenging for rare diseases/outcomes (not enough patients to follow them over time)
o loss to follow-up
o no causation, but can show association
o cost

Question 21

Case-control pros and cons?

Answer 21

PROS:
o relatively quick and cheap
o may be the only feasible method to study rare disease or long lag from exposure to outcome
o smaller sample size, good for rarer diseases
o study etiology not treatment

CONS:
o recall/record bias
o choice of controls can be problematic
o dose not deal with unanticipated confounders
o no incidence rates/relative risk
o does not determine causality or incidence

Question 22

Cross-sectional study - pros and cons?

Answer 22

PROS:
o cheap and quick and safe
o good to identify prevalence (how many cases are occurring RIGHT NOW)
o can generate 2x2 tables for comparison of groups

CONS:
o can determine association NOT causation
o does not deal at all with confounders
o cannot determine incidence

Question 23

Systematic reviews - pros and cons?

Answer 23

PROS:
o if well-conducted, can be invaluable
o can examine inconsistencies between trials
o if combining multiple small studies, can create more precise answers

CONS:
o “garbage in, garbage out”
o biases: publication, time-lag

Question 24

Sensitivity definition?

Answer 24

• sensitivity = given that the disease is present, the probability that the test is positive
• sensitivity = the proportion of people with the disease who test positive
1st column = a / (a+c)

SnNOUT – when Sensitivity is high, a Negative test rules OUT the disease (ex. urine cultures for UTI)

Question 25

Specificity definition?

Answer 25

• specificity = given that the disease is absent, the probability that the test is negative
• specificity = the proportion of people without the disease who test negative
o 2nd column = d / (b+d)

SpPIN – when Specificity is high, a Positive test rules IN the disease (ex. biopsy for diagnosing cancer)

Question 26

PPV definition?

Answer 26

• PPV = given that the test is positive, the probability that the disease is present
• PPV = the proportion of people who test positive who have the disease
o 1st row = a / (a+b)

Question 27

NPV definition?

Answer 27

• NPV = given that the test is negative, the probability that the disease is absent
• NPV = the proportion of people who test negative who don’t have the disease
o 2nd row = d / (c+d)