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The purpose of the SDTM Trial Design Model is to represent a brief, clear description of the overall plan and design of studies of tobacco products. Trial Design datasets contain study-level, rather than subject-level, information. The Trial Design datasets based on the Trial Design Model describe the planned design of the study and provide the representation of the study product in its most granular components, as well as the representation of all sequences of these components as described in the protocol.
of a nonclinical study or clinical trial. Guidance in this section is applicable only to TIG Nonclinical and Product Impact on Individual Health use cases only.In this section, the term "trial" is equivalent to "study" in the nonclinical context. Trial Design datasets contain study-level, rather than subject-level, information. Implementation of Trial Design datasets requires the explicit statement of certain decision rules that may not be addressed or may not be as explicit in the textual description of a study plan such as an approved study protocol.Concepts specific to the Trial Design Model and subsequent datasets are described below. When concepts are related to either nonclinical studies or clinical trials but not both, this is denoted in the Description column. . The TIG guides implementation of the Trial Design datasets described in the following table for use cases as indicated.
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Trial design | The design of a trial is a plan for outlining the activities subjects will experience and what data will be collected about them, in the course of the trial, to address the trial's objectives. Epoch | As part of the design of a trial, the planned periods or phases of subjects' participation are divided into epochs. Each epoch is a period of time that serves a purpose in the trial as a whole. Typically, the purpose of an epoch will be to expose subjects to a product, or to prepare for such a period (e.g., screening period, wash-out period) or to gather data on subjects after exposure to a product has ended. It is possible for epochs to span multiple elements for some or all trial arms. Arm | An arm is a planned path through the trial. This path covers the entire time of the trial. The group of subjects assigned to a planned path is also often referred to as an "arm." Each subject is assigned to 1 and only 1 planned arm. Study cell | Clinical Trials Only: Each planned path through the trial (i.e., each arm) is divided into pieces, 1 for each epoch. Each of these pieces is called a study cell. Thus, there is a study cell for each combination of arm and epoch. Each study cell represents an implementation of the purpose of its associated epoch. For an epoch whose purpose is to expose subjects to product, each study cell associated with the epoch has an associated strategy. Element | An element is a basic building block in the study or trial design. All elements are related to planned interventions, which may involve exposure to a product or no exposure to a product, during a period of time. Elements for which the planned intervention does not involve exposure to a product could include but are not limited to screening and wash-out. Study cells and elements | Clinical Trials Only:Many trials involve a single, planned exposure within a study cell. For some trials, however, the strategy associated with a study cell involves a complex series of exposures to product. In such cases it may be important to track the component steps in a strategy operationally; analyses also might require that data be grouped by the exposure step during which it was collected. The steps within a strategy may involve different exposures to product or exposure to more than one product. When the strategy for a study cell is simple, the study cell will contain a single element, and for many purposes there is little value in distinguishing between the study cell and the element. However, when the strategy for a study cell consists of a complex series of exposures, a study cell can contain multiple elements. There may be a fixed sequence of elements, or a repeating cycle of elements, or some other complex pattern. In these cases, the distinction between a study cell and an element is very useful.Branch | In a study or trial with multiple arms, the protocol plans for each subject to be assigned to 1 arm. The time at which this assignment takes place is often the point at which arms with common elements diverge and is referred to as a branch point. For many studies or trials, the assignment to an arm happens once so there is a single branch point. Subjects are assigned to an arm all at the same time. For other studies or trials, there may be two or more branches that collectively assign a subject to an arm. The process that makes this assignment may be a randomization, but this is not always the case. Products | The word product may be used in connection with epochs or elements, but has somewhat different meanings in each context:
Trial group | Nonclinical Studies Only: A trial group describes the applicant-defined protocol structure commonly used in nonclinical studies, where study subjects are allocated to study groups within the study protocol. These groups may be defined for a variety of experimental purposes. Groups are frequently defined to separate subjects receiving different treatments, but there may be other considerations involved in the design of any particular study. For purposes of SEND, a trial group is a collection of subjects which have been designated with the same sponsor-defined protocol group code. A trial group consists of 1 or more trial sets. | Trial set | Nonclinical Studies Only: A trial set is a collection of subjects that have a common set of parameters defined in the protocol, where those parameters include experimental parameters (e.g., diet restriction), treatment parameters, and/or sponsor-defined attributes (e.g., control-group designation). There should be no planned parameters of interest that could further subdivide a trial set. Each subject must be assigned to 1 and only 1 trial set. Each trial set should be assigned to a single group. Each set should be assigned to a single trial arm. | SEND | Trial set |
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| 1 | Trial Arms (TA) | Represents each planned arm in the study including the sequences of elements in each epoch for each arm. The TA and TE datasets are interrelated and provide the building blocks for subject-level information. |
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| 2 | Trial Elements (TE) | Represents the elements used in the study including unique codes for each element, element descriptions, and the rules for starting and ending an element. The TA and TE datasets are interrelated and provide the building blocks for subject-level information. |
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| 3 | Trial Visits (TV) | Represents the planned order and number of visits in the study within each arm |
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| 4 | Trial Inclusion/Exclusion (TI) | Represents the inclusion and exclusion criteria for the study |
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| 5 | Trial Summary (TS) | Represents key summary characteristics for the study |
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| 6 | Trial Sets (TX) | Represents planned sets of subjects (e.g., in vivo studies) or sources of information (e.g., in vitro studies) that result from combinations of experimental factors defined for the study |
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