Evidence Based Dentistry

Question 1

What is a Systematic Review?

Answer 1

A type of literature review that uses systematic methods to collect secondary data, critically appraise research studies and synthesise studies

Question 2

What are the benefits of systematic reviews?

Answer 2

Saves readers time
Provide reliable evidence
Resolve inconsistencies
Identify gaps
Identify when questions have been fully answered
Explore differences between studies

Question 3

What are the key characteristics (5) of a systematic review?

Answer 3

Well formulated question
Comprehensive data search
Unbiased selection and abstraction process
Assessment of papers
Synthesis of data

Question 4

Why are systematic reviews important?

Answer 4

Reduce large quantities of information into manageable portions
Formulate policy and develop guidelines
Efficient use of resources
Increased power/precision
Limit bias and improve accuracy

Question 5

What is the Cochrane Collaboration?

Answer 5

Global independent network
Provides a powerful tool to enhance your healthcare knowledge and decision making
Gathers and summarises the best evidence from research to help you make informed choices about treatment

Question 6

In forest plots what does I squared value represent?
What % is acceptable

Answer 6

Level of statistical heterogeneity
<50% is acceptable

Question 7

What does PICO stand for?

Answer 7

Participants
Interventions (exposure)
Comparisons
Outcomes

Question 8

What is more likely to happen to statistically significant ‘positive’ results?

Answer 8

More likely to be published (publication bias)
More likely to be published rapidly (time lag bias)
More likely to be published in English (language bias)
More likely to be cited by others (citation bias)

Question 9

What does unbiased selection and abstraction process include?

Answer 9

Selection of relevant papers
Data extraction to a predefined data extraction form
Process should be conducted independently by at least 2 reviewers
Clear description of reasons for exclusion
Adequate description of included studies
Details of studies funding sources

Question 10

What are composite scales?

Answer 10

‘Quality’ Assessment Tool
Assign numerical value to individual items to provide overall estimates of quality
NOT preferred method

Question 11

What is a component approach?

Answer 11

‘Quality’ Assessment Tool
Assess relevant methodological aspects individually (e.g. randomisation, blinding, drop-outs)
PREFERRED method

Question 12

What is bias?

Answer 12

Bias determines the extent to which results of studies can be believed (low risk of bias= higher belief in results)

Question 13

What is included in a risk of bias assessment for RCT’s?

Answer 13

Sequence generation (selection bias)
Allocation concealment (selection bias)
Blinding (participants/outcome assessors)
Incomplete outcome data (attrition bias)
Selective outcome reporting (reporting bias)
Other bias

Question 14

What type of information does a meta-analysis include?

Answer 14

Quantitative

Question 15

What is a meta-analysis?

Answer 15

The process of using statistical methods to combine the results of different studies
Aim is to integrate the findings, pool the data, and identify the overall trend of results
Calculates a treatment effect based on pooled data from a group of studies

Question 16

What are the potential advantages of a meta-analysis?

Answer 16

Increase in power
Improvement in precision
Ability to answer questions not posed by individual studies

Question 17

What is Dichotomous data ?

Answer 17

Binary data
Illness or not/death or not/birth or not
Comes in one of 2 forms (either are or are not)

Question 18

What is Continuous data?

Answer 18

Blood pressure/weight/amount of pain
Quantitative data that is measured to the precision of what you are measuring

Question 19

What sorts of summary statistics are included in Dichotomous data?

Answer 19

Odds ratio
Risk ratio
Percent risk reduction or relative risk reduction (RRR)
Risk difference, or absolute risk reduction (RD)
Number needed to treat (NNT) (1/RD)

Question 20

What kinds of summary statistics come under Continuous data?

Answer 20

Weighted mean difference
Standardised mean difference

Question 21

When weighting studies what is more weight given to?

Answer 21

More participants
More events
Lower variance

Question 22

What is the line of no effect in forest plots?

Answer 22

Vertical line in the middle where the intervention and control have the same effect
If the study sits here there is no difference between the treatment and the control

Question 23

What shape is given to the pooled analysis in a forest plot?

Answer 23

Diamond

Question 24

What is Heterogeneity?

Answer 24

Refers to the variability or differences observed among studies

Question 25

What is clinical heterogeneity?

Answer 25

Variation in participants, interventions, outcomes and study design
Ways the different studies are conducted

Question 26

What is methodological heterogeneity?

Answer 26

Variation in methods used in studies e.g. quality of allocation concealment

Question 27

What is statistical heterogeneity?
How does this appear in forest plots as?

Answer 27

Excessive variation in the results of studies
Variation in treatment effects above that expected by chance
May appear in a forest plot as poor overlap of confidence intervals

Question 28

What is the test for heterogeneity?
What P value demonstrates statistically significant heterogeneity?

Answer 28

Chi-squared test of heterogeneity
P<0.1 demonstrates statistically significant heterogeneity

Question 29

What does GRADE stand for? What is it used for

Answer 29

Grading of Recommendations Assessment, Development and Evaluation
Evaluates the quality of the body of evidence

Question 30

What does a summary of findings table include?

Answer 30

Summary of the key findings from a systematic review
It presents quality of the evidence, magnitude of the effect and reasons behind the judgements

Question 31

What is incidence?

Answer 31

Number of new cases over a specific time

Question 32

What is prevalence?

Answer 32

Number of cases at a time