Type of Research Design II

Question 1

What type of study starts with the Exposure and inquires the outcome

Answer 1

case control study

Question 2

What type of study starts with the outcome and inquires the exposure (present to future)

Answer 2

prospective cohort study

Question 3

What type of study starts with the outcome and inquires the exposure (past to present)

Answer 3

retrospective case control study

Question 4

What type of study asks the exposure and outcome at the same time

Answer 4

cross sectional

Question 5

What are the advantages of cohort studies? 4

Answer 5

 Temporal relationship (what comes first) between exposure & disease can be established
 Can examine relationship between a single exposure & one or more
conditions
 Useful when the exposure is rare
 Minimal selection & recall bias as compared to case-control studies

Question 6

What are disadvantages to cohort studies? 6

Answer 6

 Not very useful to study very rare diseases
 Lossesto follow-up
 Requires large sample
 Long time to complete
 Expensive & difficult to manage
 Exposure status can change with long follow-up

Question 7

When do you use odds ratio?

Answer 7

Case control study

Question 8

When do you use risk ratio?

Answer 8

Cohort and clinical trials

Question 9

Which epidemiological study uses incidence as a measure of frequency?

Answer 9

cohort and clinical trials

Question 10

What is incidence?

Answer 10

Number of people with the disease over number of people at risk

Question 11

Why are odds ratio less reliable than relative risk?

Answer 11

When outcome is common, odds ratio tend to overestimate the odds of the disease

Question 12

When are odds ratio and relative ratio the same?

Answer 12

When outcome is rare

Question 13

What is a baseline risk?

Answer 13

the common risk of getting a certain disease without any exposures

Question 14

what is the name of the risks that are due to the presence of exposures?

Answer 14

excess risk

Question 15

What is attributable risk?

Answer 15

the portion of the incidence of a given disease in the exposed that is due to the exposure

Question 16

What are the advantages of randomized control trials? 5

Answer 16

 Gold standard design for examining treatment’s efficacy
 Clear eligibility criteria & exposure
 Minimal bias if conducted appropriately
Selection bias & confounding are minimized by randomization & allocation concealment
Measurement bias (performance & detection) is minimized by blinding participants & investigators to group allocation

Question 17

What is the disadvantages of randomized controlled trials

Answer 17

 Expensive
 Volunteering bias
 Loss to follow-up bias (can be minimized by intention to treat analysis)

Question 18

What is the intention to treat analysis?

Answer 18

all subjects randomized are included in the primary outcome analysis at the end of the study, even if they have dropped out

Question 19

How to interpret NNT?

Answer 19

for every (no.) patient undergoing (exposure) treatment, 1 fall will be prevented as compared with (none exposure group)

Question 20

Advantages of NNT and NNH?

Answer 20

 Clinically meaningful way of expressing the benefit of an intervention over another
 Take the absolute risk of the event into account
 Assist in clinical decision making

Question 21

What is the name of experiments that are not randomized?

Answer 21

Quasi-expirements

Question 22

What is the advantages of Quasi experiments?

Answer 22

 Less expensive (require fewer resources)
 Useful in evaluation of rapid responses to outbreaks & patient safety
problems

Question 23

What are the disadvantages of Quasi experiments? 5

Answer 23

 Participants are not assigned randomly intervention & comparison group
 Non-equivalent groups design: confounding & internal validity issues
(uncertainty of causal inference)
• Participants are not assigned randomly intervention & comparison group
• Participants in intervention & control groups may differ in known &
unknown confounders (non-equivalent groups design)
• Non-equivalent groups design threatens internal validity (the degree of confidence that the intervention was responsible for the outcome in the intervention group

Question 24

What are systematic reviews?

Answer 24

Are studies of studies that offer a systematic approach to reviewing & summarizing evidence a bout a particular research question

Question 25

What are the key characteristics of a systematic review? 5

Answer 25

• A set of objectives with pre-defined inclusion criteria • Comprehensive searches to identify all relevant studies • Assessment of the quality of included studies (risk of bias assessment) • A standardized presentation & synthesis of the characteristics & findings of the included studies • At least two reviewers are involved

Question 26

What are the key roles & importance of systematic reviews? 6

Answer 26

• Keep up to date with constantly expanding number of studies • Critically appraise primary studies addressing the same research question  Investigate possible reasons for conflicting results • Provide more precise & reliable effect estimates than is possible from individual studies • Identify gaps in the evidence base • Make evidence-based decisions & to inform the development of clinical guidelines

Question 27

What are the advantages of systematic reviews? 3

Answer 27

 Less costly than RCTs  Stronger external validity  Considered an evidence-based resource

Question 28

What are the disadvantages of systematic reviews? 4

Answer 28

 Time-consuming  Heterogeneity of studies  May not be easy to combine studies results  Reporting (publication & language) bias