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Where Do Target Trials Come From? Specifying the Protocol of a Target Trial When Repurposing Data for Causal

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Developing a target trial protocol using existing data requires iterative adaptation. Investigators must adjust the protocol based on data exploration, making prespecification challenging and raising questions about transparency and permissible data use.

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Area of Science:

  • Epidemiology
  • Causal Inference
  • Health Data Science

Background:

  • The target trial framework often assumes upfront knowledge of the trial protocol.
  • In practice, observational data constrains and shapes the target trial protocol, especially when using pre-existing databases.
  • Iterative development of the target trial protocol is common as investigators interact with available data.

Purpose of the Study:

  • To examine how investigators adapt their initial causal questions and index trial protocols to available observational data.
  • To understand the process leading to a final target trial protocol that is influenced by both the original question and the data.
  • To address the implications of data-driven protocol adaptation for prespecification and transparency.

Main Methods:

  • Conceptual analysis of the target trial framework in the context of real-world data use.
  • Examination of the adaptive process in developing target trial protocols from observational data.
  • Discussion of the challenges posed by data-dependent protocol specification.

Main Results:

  • The target trial protocol is typically adapted iteratively based on available observational data.
  • The final protocol depends on both the initial causal question and insights gained from data inspection.
  • Prespecification of an emulatable target trial protocol is often not feasible due to expected data-driven adaptations.

Conclusions:

  • The adaptive nature of target trial protocol specification necessitates careful consideration of permissible data examinations.
  • Transparent reporting of adaptations and their rationales is crucial.
  • Further research is needed on prespecifying rules for data-driven protocol modifications.