Randomized Controlled Trials

Question 1

When should stratified allocation be utilized?

Answer 1

• when there are two groups with different characteristics
• useful in smaller trials

Question 2

What is stratified allocation?

Answer 2

• more than one randomization table
• one for people without baseline characteristics and one for people with a characteristic
• assure baseline factor that impact study outcome equally distributed in study groups

Question 3

What is the 2x2 factorial design?

Answer 3

• all participants are randomized to one therapy or another
• everyone is randomized to a second therapy or another

Question 4

How do you determine if randomization worked?

Answer 4

• Evaluate the baseline characteristics of the patient enrolled
• look for statistical (p-value) and clinical differences (your judgement)

Question 5

What is cluster randomization?

Answer 5

• sites are randomized to recieve intervention or control therapy
• easier for individuals at a site to predict if their site is giving intervention or control which can cause selection bias

Question 6

What are the benefits of allocation concealment?

Answer 6

• protects assignment of random sequence from person enrolling participant until enrollment
• prevents selection bias

Question 7

What are key words for concealment allocation?

Answer 7

• sequentially numbered, opaque, sealed envelopes
• sequentially numbered containers
• pharmacy controlled
• central randomization

Question 8

What is blinding?

Answer 8

withholding information about the assigned interventions from people involved in the trial who could be influenced

Question 9

Why would blinding be beneficial?

Answer 9

helps protect what randomization has achieved from the time interventions assigned to the end of the trial and data analysis

Question 10

Why would blinding be beneficial?

Answer 10

helps protect what randomization has achieved from the time interventions assigned to the end of the trial and data analysis

Question 11

What are the different types of blinding?

Answer 11

• unblinded or open label
• single blinded
• double blinded

Question 12

Whar are the differences between blinding and allocation concealment?

Answer 12

• Allocation concealment: prevent selection bias, can always be successfully implemented
• Blinding: prevent performace and ascertainment bias, protect the random sequence after allocation, cannot always be implemented

Question 13

How could lack of blinding influence trial results– subjects?

Answer 13

placebo effect, risk of dropping out, adherence, biased report of subject outcomes

Question 14

How could lack of blinding influence trial results– healthcare providers?

Answer 14

more likely to screen for problems if on placebo/control, differential co-interventions

Question 15

How could lack of blinding influence trial results– data collectors?

Answer 15

biased collection “looking” fir outcomes with variable intensity, repear measures of abnormal findings

Question 16

What are the different types of control groups?

Answer 16

• Untreated control: experiemental therapy vs no therapy or experimental therapy + baseline therapy vs baseline therapy alone
• placebo control: experimental therapy vs placebo therapy
• active control: experimental therapy vs active therapy