Evidence based dentistry

Question 1

What studies can be used for epidemiology?

Answer 1

• Randomised controlled trials
• Cohort studies
• Case control studies

Question 2

Describe a randomised control trial used for epidemiology?

Answer 2

• Gold standard study design for effectiveness and efficacy when comparing effectiveness of one treatment to another
• Provide the strangers evidence on the effectiveness of treatments in clinical trials

Question 3

Describe cohort studies for epidemiology?

Answer 3

• Prospective studies which recruit groups of people who have not manifested disease at time of recruitment and you assess the risk factors
• Individuals observed over period of time to measure frequency of occurence of disease, amount of people exposed to risk factor and people not exposed

Question 4

Describe Case control studies for epidemiology?

Answer 4

• Retrospective study which compares individuals with disease (cases) with those without disease (controls)
• Then trace back to assess risk factors through past histories and exposure to suspected harmful agents compared
• Less robust than cohort studies but can be used as preliminary investigations of hypothesis followed by cohort

Question 5

How do you determine significance?

Answer 5

• When confidence intervals do not overlap
• If P values less than 0.05 then stastistically significant

Question 6

What is critical appraisal?

Answer 6

• Process of assessing and interpreting evidence through systemic consideration of its validity, relevance and results

Question 7

What is CASP?

Answer 7

• Critical Appraisal Skills Programme

Question 8

What do you need to consider when evaluating results?

Answer 8

• Are they valid?
• What are the results?
• Are the results relevant to your clinical practice? i.e. any adverse effects or clinically important outcomes

Question 9

How can you see if results of trial are valid?

Answer 9

• Use PICO
• How was study conducted (randomisation, blinding, allocation concealment, flow of participants)

Question 10

How can you analyse what the results are?

Answer 10

• Precision CIs
• What has been measured and how large?

Question 11

What is PICO?

Answer 11

• Population
• Intervention
• Comparison
• Outcome

When evaluating study use this to determine what the study is telling you

Question 12

How to determine (absolute) risk difference? Example

Answer 12

• It is the risk between groups
• ‘Risk’ or ‘chance’ of at least 50% pain relief in 4hours
• Good outcome measure =
  Risk in paracetamol group is pain relief yes/total paracetamol
  Risk in placebo group is pain relief yes/total placebo
  Calculate risk difference = risk in paracetamol - risk in placebo
• % more pt experience pain relief in paracetamol group = ARD
• Calculate confidence interval

Question 13

What is Confidence interval?

Answer 13

• Range that the ARD with take in population
• 95times/100 CI will contain TRUE ARD

Question 14

With a value of ‘no difference’ = 0 what should 95% CI not overlap if sufficient evidence?

Answer 14

• Should not overlap 0

Question 15

What is the Number Needed to Treat NNT?

Answer 15

• Number of patients you would need to treat to prevent one patient from developing the disease/condition/outcome
  = 1/Absolute Risk Difference

Question 16

What other pieces of info would you need to decide if one thing is better than other?

Answer 16

• Odds ratio (OR)
• Relative risk or risk ratio (RR)
• Percent risk reduction or relative risk reduction (RRR)
• Risk difference or absolute risk reduction (RD)
• Number needed to treat (NNT) = (1/RD)

Question 17

What is SIMD?

Answer 17

• Scottish Index of Multiple Deprivation

Question 18

What is the SIMD?

Answer 18

• Looks to extent area is deprived across seven domains
• Income
• Employment
• Education
• Health
• Access to services
• Crime
• Housing
• Most deprived ranked 1
• Least deprived 6976