Spring Intro 2023

16/02/2023

Double Dummy

Problem

You want to perform a double-blind trial comparing a nicotine replacement patch with chewing gum • Patients will not be blinded (the difference between sticking on a patch and chewing some gum is obvious!) • Investigators will almost certainly be unblinded as well - “I don’t like the taste” - “It makes my arm itch”

Solution

All patients use a gum AND a patch:

• Active gum plus placebo patch

…but nobody knows which is which

• Placebo gum plus active patch

The Organisation for Professionals in Regulatory Affairs

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Stratification

Problem

Solution

Arrange randomisation to take account of the patient’s sub-group:

You might need to assess safety and efficacy in specific patient sub-groups

1. Establish status (e.g. male vs female) 2. Randomise to treatment arm

- Young vs old - Men vs women - Moderate vs severe disease

The statisticians will need the treatment groups to be evenly balanced between the treatment arms

Be careful not to over-complicate stratification

!

The Organisation for Professionals in Regulatory Affairs

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