Which describes the New User Design?

• A. Include prevalent users
• B. Randomizes exposure
• C. Only initiators
• D. Uses cross-over design

Answer: (C)

New-User Design focuses on studying people at the moment they start a therapy and includes only those who are new users, excluding anyone with prior exposure to the drug. This approach reduces biases that come from mixing initiators with people who have already been on the treatment for some time, such as differences in risk profiles, duration of exposure, or the possibility that only those who tolerated the drug continued using it. By starting follow-up at initiation, you align the exposure and outcome assessment and minimize immortal time bias, making the comparison between users and non-users more valid.

Including prevalent users would introduce these biases because their past exposure and survivorship could skew safety and effectiveness results. Randomizing exposure describes a different study design (experimental, not observational), and a cross-over design is a separate approach where individuals receive multiple interventions in sequence. The best description of the New-User Design is focusing on initiators only.