trial design

Question 1

superiority trial

Answer 1

Determine whether a new intervention
is better or worse than the control

typically comparator is a placebo

Question 2

non-inferiority trial

Answer 2

Determine whether a new
intervention is no worse (but can be better) than the
control

Question 3

equivelance trial

Answer 3

Determine whether one intervention is
therapeutically “similar” (i.e. neither better nor
worse) to another

Question 4

when does an equivelance trial deem a treatment equivelance

Answer 4

if the treatment effect iles within a pre defined set of limits (called an equivelance margin)

Question 5

when does a non inferiortiy trial deem a new treatment as non-inferior

Answer 5

when the treatment effect is not worse than the control by more than a pre-specified amount

known as the non-inferiority margin or delta

Question 6

rallel designphase 0 trial

Answer 6

2 groups, each independently followed up

Question 7

multi-arm trial

Answer 7

n randomised into multiple arms (more than 2)

• Head-to-head comparison of several treatment
  strategies, e.g. different doses, different drugs, more
  than one control group.

Question 8

what, in the design phase do we need to consider for when having a multi-arm trial?

Answer 8

needs consideration for “multiple-testing” in the sample size
calculation.

multiplicity of comparisons. with more treatment arms, the issue of multiplicity increases

A study with 4 treatment arms results

• 6 possible pairwise comparisons
• 19 ways of pooling and comparing two groups
• 24 ways of ordering the arms
• grand total of 50 possible hypothesis tests

formal adjustment for multiple comparisons need to be considered.

Question 9

trial:

examines optimal dose of ketamine as a general anesthesia.

3 treatment arms (doses 0.25, 0.5, and 1mg/kg) and 1 control arm (placebo.

what kind of deisgn is this?

Answer 9

multi-arm trial

Question 10

factorial design

Answer 10

a design where two interventions are compared to a placebo. Essentially 2 (or more) treatments in 1.

Question 11

cross over trial

Answer 11

• Repeated measures design.
• Each participant is exposed to both the control and the
  intervention.
• Can be more efficient than a parallel design.
• BUT condition must be chronic and stable.
• Preferred design for bioequivalence trials.

Question 12

main disadvantage of a crossover trial

Answer 12

• Carryover effects may be confounded with the direct intervention effect.
• Attempts to mitigate this w washout period.
• Longer duration of trial
• Patients may drop out after the 1
  st treatment
• Only certain diseases/conditions are suitable
• Defining an adequate washout period
• Carry-over effects
• Period effects

Question 13

main advantages of cross over trial

Answer 13

• Fewer patients (and often fewer assessments)
  needed to achieve a specific power than in a
  parallel group trial - potential financial savings
• Each patient gets all the treatments - may help
  recruitment
• Patients act as their own control -