Week 5

Question 1

define inference

Answer 1

an educated statement about an unknown population

Question 2

define causal inference

Answer 2

conclusion made about a population from the study of a sample of that population
(determine if effect was caused by association or a direct effect)

Question 3

define critical appraisal

Answer 3

A systematic process used to identify the strengths and weaknesses of a research article in order to assess the usefulness and validity of research findings

Question 4

what are examples of objective outcomes related to patients?

Answer 4

delayed or reduced rates of death (mortality)
reduced disease incidence (morbidity)

Question 5

what are examples of subjective outcomes related to patients?

Answer 5

Symptom relief
Emotional/Mental/Physical Functioning
Health-Related Quality of Life
(all based on scales or scores)

Question 6

T/F experiments with subjective outcomes are more difficult to repeat and are thus more reliable

Answer 6

false, less reliable

Question 7

what are examples of continuous data objective outcomes?

Answer 7

lab values
blood pressure
weight
(these outcomes can highly vary… BP can change continuously)

Question 8

what are examples of nominal data objective outcomes?

Answer 8

death
has the patient had an MI
(these outcomes cannot revert back… a dead pt will not become alive)

Question 9

what question should be asked in regards to the reliability of subjective information?

Answer 9

has minimal clinically important difference (MCID) been established?

Question 10

what is minimal clinically important difference (MCID)?

Answer 10

you must determine if the data is actually important. just because it may be statistically significant does not make it clinically significant. for example: a change in BP of 5 could be considered statistically significant, but as clinicians we are able to determine that BP highly fluctuates and we cannot immediately conclude that the change in BP was due to a studies intervention

Question 11

Subjective outcomes assessed with surveys & scales need to establish?

Answer 11

validity, reliability, and minimal clinically important difference

Question 12

define what a surrogate endpoint is

Answer 12

A laboratory measurement or physical sign that is used in therapeutic trials as a substitute for a clinically meaningful end point that is a direct measure of how a patient feels, functions, or survives, and that is expected to predict the effect of therapy

Question 13

explain an example of a surrogate endpoint associated with diabetes

Answer 13

if we are doing a study on how insulin medication benefits patients with diabetes, the true clinical outcome that we care about is reduction in death due to use of insulin. a surrogate endpoint can be used instead to try and show significance of a drug’s benefit. For example, we can measure a patients HbA1C after insulin treatment or fasting glucose after insulin treatment to see insulin’s impact on these factors. These factors are ASSOCIATIONS with insulin use, but are not CAUSATIONS showing insulin’s direct impact on mortality.

Question 14

what’s another example of a surrogate endpoint associated with osteoporosis?

Answer 14

a clinically meaningful endpoint in regards to osteoporosis is incidence of fractures. a surrogate endpoint could be associating bone mineral density values with the risk of fracture

Question 15

what are the advantages of surrogate endpoints?

Answer 15

Smaller sample size; expose fewer patients
Shorter trials / faster to market
Easier to measure
Less invasive for patients

Question 16

what are the disadvantages of surrogate endpoints?

Answer 16

Trial too short to evaluate long-term side-effects
Patients don’t relate their clinical experience to surrogate
Intervention may affect surrogate endpoint but not clinical outcome

Question 17

T/F surrogate endpoint evaluation cannot be established with a single RCT

Answer 17

true

Question 18

T/F surrogate endpoints usually show clinical relevancy for patients

Answer 18

false

Question 19

what does it mean to say that a surrogate endpoint must determine clinically relevant levels of change?

Answer 19

the surrogate endpoint must be able to prove that it is clinically relevant towards the true outcome in order for it to be considered clinically significant (ex. a drug that on average decreases BP by 10 was determined to reduce CV death by 10%)

Question 20

define composite outcomes
explain its use with an example

Answer 20

a collection of multiple outcomes combined into one outcome
an outcome such as CV death has numerous variables attributing to it and can be caused by numerous variables (MI, stroke). A composite outcome study studies the occurrence of these variables to determine how the drug of interest reduces said variables to overall reduce CV death

Question 21

what are components of a composite outcome study that are required to show significance?

Answer 21

-the variables in the study must be associated with the true outcome (incidence of MI and GI bleed are not associated with the same outcome)
-the components should be similarly important (asthma-related death & administration of an oral corticosteroid are not related to each other)
- the incidence should be similar for all components
-the treatment effect should be similar for all components (similar risk ratios)

Question 22

what are the 4 key components of the critical appraisal of studies?

Answer 22

-validity
-reliability
-importance
-applicability

Question 23

what is internal validity?

Answer 23

validity within the confines of the study methods: does it appropriately test/measure what it proposed? does it appropriately address bias, confounding, and measurement of endpoints?

Question 24

what is external validity?

Answer 24

validity related to generalizing the study results outside the study setting: can the results be applied to other groups, patients, or systems?

Question 25

define data maturation

Answer 25

when external changes occur within subjects which may explain in part or in total for effects discerned in the study rather than being caused by the study intervention
ex. a study reporting decrease in ED visits in a study of children with asthma may be because they outgrew childhood asthma rather than because of the treatment given

Question 26

define repetitive testing

Answer 26

when changes in test scores occur not because of the intervention but because of repeated testing

Question 27

define instrumentation

Answer 27

when study results are due to changes in instrument calibration or observer changes rather than an actual treatment effect

Question 28

define regression

Answer 28

when subjects are chosen on the basis of extreme scores and therefore the study outcome cannot be accurately assessed

Question 29

define differential selection

Answer 29

when subjects cannot be randomized into groups, particularly if groups are unequal in relevant variables before treatment intervention
example: one group is given an educational counsel of the treatment trial while the other group is given a mailed pamphlet. the first group will be more informed of the study and therefore the two groups are not equal with respect to relevant variables

Question 30

define attrition

Answer 30

aka withdrawals or dropouts. problematic when subjects leave the study and cause the different groups in the trial to be significantly unequal. This can skew how beneficial/unbeneficial the treatment actually is

Question 31

repetitive testing, instrumentation, regression, differential selection, and attrition are all examples of?

Answer 31

factors that affect a study’s internal validity

Question 32

define study reliability (aka test, re-test reliability))

Answer 32

refers to the degree to which an instrument yields consistent results
—> if research is repeated and shows the same results each time then we can say the research design is reliable

Question 33

what is IMRAD?

Answer 33

the most standard structuring for creating a study paper. it stands for:
Introduction- the why
Methods- how they did it and how they analyzed the results
Results
And
Discussion- what the results mean

Question 34

what does it mean to develop a cognitive map?

Answer 34

the research paper describes the analytical process and guides the logic. the information provides a complete description of each internal-validity problem