Prevalent New User Designs: State of the Science and Considerations for Complex Clinical Scenarios

Background: The prevalent new user design (PNU) has been increasingly used in pharmacoepidemiologic research over the last several years. However, its use has been limited to a small number of clinical areas, most frequently type 2 diabetes, and little is known about its implementation in more complex clinical scenarios, including complex treatment pathways where numerous treatment options are available, cumulative effects, and evolving disease severity. These settings are likely to result in heterogenous prevalent users who may have used multiple prior treatments in a variety of sequences (e.g., multiple sclerosis, rheumatoid arthritis), and it is unknown if a traditional PNU implementation addresses the biases associated with the study of prevalent users in these scenarios.

Objectives: This symposium aims to describe the PNU design and explore its extension to settings in which the patients of interest have complex clinical scenarios. The learning objectives for the symposium are:
1. To describe the prevalent new user design and its use in practice.
2. To recognize clinical scenarios where the traditional PNU implementation may be not sufficient in terms of bias reduction.
3. To explore different methodological approaches in which the PNU design can be expanded to address complex clinical scenarios.

This symposium will benefit researchers with a variety of interests and varying expertise who would like to implement the PNU, clinicians treating patients in complex clinical scenarios, and knowledge users who want to understand the real-world impact of newly-marketed drugs in clinical areas with dynamic treatment pathways.

Description: This symposium will have five leading researchers from across the world in the implementation of the PNU:
Dr. Webster-Clark will describe the PNU and the rationale for using it (20 minutes).
Dr. Tazare will describe the clinical applications and methodological implementation of the PNU to date (20 minutes).
Prof. Burden will explore potential clinical settings where the traditional implementation of the PNU is unlikely to adequately address potential confounding due to prior use, disease history, and disease severity (10 minutes).
Dr. Filion will present the results of a simulation study examining the implementation of the PNU in a population that reflects treatment patterns for a complex clinical scenario and a newly-marketed drug (20 minutes).
Prof. Pratt will moderate the symposium and lead a panel discussion. This panel discussion will facilitate dialogue between methodologists and clinical experts on the consequences for appropriately addressing emerging clinically and policy relevant research questions with a PNU design (20 minutes).