Critical Appriasal

Question 1

Best trial for comparing effectiveness of two treatments?

Answer 1

Randomised control trial

Question 2

What are the main questions when critically appraising?

Answer 2

Are results valid?

Question 3

What makes results valid?

Answer 3

PICO

Treatment assignment randomised

All those who start trial are accounted for at the end

Were any individuals blind to any of the treatment

Were groups similar at the start of trial e.g. smokers, gender etc

Were groups treated equally other than medical intervention

Question 4

What is risk difference?

Answer 4

E.g. study on paracetamol for pain relief

Non placebo 40/63 had pain relief = 63%

Placebo 5/27 had pain relief = 18%

63 - 18 = 45% risk difference

Question 5

What are confidence intervals?

Answer 5

The range of values the ARD will take in the population

95% CI should not overlap 0

Question 6

What is NNT?

Answer 6

Number needed to treat

Number of patients needed to treat in order to prevent one patient from developing the disease/condition or outcome

1 / ARD

Paracetamol e.g. 1 / 0.45 = 2.22 so 3 people

Question 7

What is a cohort study

Answer 7

Group free of disease is taken

Split into one group who have been exposed to a risk factor

One who has not

Follow them and see disease prevalence in each group

Question 8

Pros / cons of cohort study?

Answer 8

Pros = more ethical than a RCT as not holding back treatment from one other

Goof at evaluating a frequency of disease incidence when exposed to a certain risk factor

Cons = long time of recall can lose study participants
No blinding or masking
Not randomly selected