Critical appraisal

Question 1

4 steps of the process of critical appraisal

Answer 1

1. Come up with an answerable question
2. Search for best evidence
3. Appraise the evidence
4. Make a decision

Question 2

What contributes to making a final decision?

Answer 2

Available evidence, available resources, patient preference, clinical experience

Question 3

What does PICO stand for?

Answer 3

P = patient, problem, population
I = intervention 
C = comparason, comparator, control
O = outcome

Question 4

When you have a study you cannot control (e.g. about risk factors), what type of question do you use?

Answer 4

PEO question

Question 5

What does PEO stand for?

Answer 5

P = patient group 
E = exposure
O = outcome

Question 6

Name 5 types of question we can have?

Answer 6

1. Therapy
2. Prognosis
3. Diagnosis
4. Aetiology
5. Evaluation/acceptance

Question 7

Best feasible study design for diagnosis

Answer 7

Cross-sectional analytic study

Question 8

What is a cross-sectional analytic study?

Answer 8

Looks at data from a cross-section of a population from the same time point

Question 9

Best feasible study design for aetiology (harm)

Answer 9

Cohort study (prospective), population-based case-control study (retrospective)

Question 10

Best feasible study design for prognosis

Answer 10

Cohort study

Question 11

Best feasible study design for treatment

Answer 11

RCT, systematic review (SR) of RCTs

Question 12

Best feasible study design for evaluation

Answer 12

Qualitative research (SR or meta-analysis also possible).

Question 13

What is a systematic review?

Answer 13

critcially appraises all available research on a particular topic.

Question 14

Potential benefits of systematic reviews over primary individual trials

Answer 14

• Include all available evidence to answer a question
• Include research that is unpublished or published in non-English-language journals
• Increase the total sample size (increases levels of certainty and precision)
• indicate heterogeneity (variation) among studies
• permit sub-group analysis
• permit sensitivity analysis

Question 15

What is a sub-group analysis?

Answer 15

Evaluation of treatment effects for a specific end point in subgroups of patients determined by a baseline characteristic

Question 16

What is sensitivity analysis?

Answer 16

Are the results sensitive to the quality of the research? e.g. looking at top 10 studies

Question 17

What is bias?

Answer 17

systemic introduction of error into a study that can distort the results in a non-random way

Question 18

What is error?

Answer 18

difference between the average values that were obtained through a study and the true average values of the population

Question 19

error vs bias

Answer 19

Every study has some degree of error. Bias is systemic and non-random.

Question 20

4 things you should assess a research study for

Answer 20

1. Bias
2. Applicability
3. Limits
4. Values

Question 21

3 steps to the appraisal of the results of a study (questions)

Answer 21

1. Are the results of the study valid?
2. What are the results?
3. Can the results apply to patient care?

Question 22

What is study validity?

Answer 22

The believability or credibility of the results. Do they represent an unbiased estimate of the treatment effect or have they been influenced in some systematic fashion?

Question 23

NNT

Answer 23

Number needed to treat

Question 24

NNH

Answer 24

Number needed to harm

Question 25

Define NNT

Answer 25

Number of patients you need to treat to prevent one additional bad outcome.

Question 26

Define NNH

Answer 26

How many persons on average need to be exposed to a risk factor over a specific period to cause harm in an average of one person who would not otherwise have been harmed

Question 27

What is generalisability of results

Answer 27

The extent to which research findings can be applied to settings other than that in which they were orignially tested

Question 28

What is particularisability

Answer 28

Can you use this evidence to inform the decisions you make about this particular patient/answer this particular question?
- How similar or patient in the study to yours?
- Can local health service provide it?
What are the benefits and costs?

Question 29

What are the 2 screening questions which, if the answer is no, the study shouldn’t continue?

Answer 29

Did the review ask a clearly-focused question

Did the review include the right type of study?

Question 30

What should a search strategy include?

Answer 30

Hand-searching, conference proceedings, contacting authors and papers in languages other than English

Question 31

Why include none English-language papers?

Answer 31

Increase population size, not including may over-state effect size as it usually excludes papers with null rsults.

Question 32

When should you combine results in a meta-analysis?

Answer 32

When studies are similar/same outcomes

Question 33

What is the line at 0 in a meta-analysis graph called?

Answer 33

Line of no effect