Steps for Representing Trial Design

The following are recommended steps to support implementation of Trial Design datasets. Implementers are encouraged to start with representation of more-familiar concepts, such as arms, and move to less-familiar concepts, such as elements and epochs. In practice, the actual process to implement Trial Design datasets may depart from these steps with some steps overlapping and some steps not relevant to a specific study design.  When steps or aspects of steps are specific to Product Impact on Individual Health use cases only, this is denoted in the step.

1. Start with a clear understanding of your study design based on the protocol, especially the distinct paths of activities subjects will experience that spans the entire study. These paths are the arms for the study. Each path can have decision points where the paths diverge based on some criteria.
   1. Product Impact on Individual Health only: Start from the flow chart or schema diagram usually included in the protocol. This diagram will show how many arms the study has, and the branch points or decision points where the arms diverge.
2. Write down the decision rule for each branching point in the diagram. Does the assignment of a subject to an arm depend on a randomization? On whether the subject responded to a study assessment? On some other criterion?
3. If the study has multiple branching points, check whether all the branches that have been identified really lead to different arms. The arms will relate to the major comparisons the study is designed to address. For some studies, there may be a group of somewhat different paths through the study that are all considered to belong to a single arm.
4. For each arm, identify the major time periods of evaluations of the tobacco product, a subject assigned to that arm will go through. These are the elements, or building blocks, of which the arm is composed.
5. Define the starting point of each element. Define the rule for how long the element should last. Determine whether the element is of fixed duration.
6. Re-examine the sequences of elements that make up the various arms and consider alternative element definitions. Would it be better to “split” some elements into smaller pieces or “lump” some elements into larger pieces? Such decisions will depend on the aims of the study and plans for analysis.
7. Compare the various arms and, where appropriate, define epochs.
   
   1. Product Impact on Individual Health only: In most studies especially blinded studies, the pattern of elements will be similar for all arms, and it will make sense to define epochs. Assign names to these epochs. During the conduct of a blinded study, it will not be known which arm a subject has been assigned to, or which product exposure elements they are experiencing, but the epochs they are passing through will be known.
8. Product Impact on Individual Health only: Identify the visits planned for the study. Define the planned start timings for each visit, expressed relative to the ordered sequences of elements that make up the arms. Define the rules for when each visit should end.
9. Product Impact on Individual Health only: Identify the inclusion and exclusion criteria to be able to populate the Trial Inclusion/Exclusion Criteria (TI) dataset. If inclusion and exclusion criteria were amended so that subjects entered under different versions, populate TIVERS to represent the different versions.
10. Populate the TS dataset with summary information.