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Modeling a nonclinical study in this standardized way requires the explicit statement of certain decision rules that may not be addressed or may not be as explicit in the textual description of the approved study protocol (or study plan). Prospective modeling of the design of a study could contribute to a more complete and wholly representative protocol. Retrospective modeling of the study design provides a Reviewer with a clear description of how the study was conducted.

Trial Design Concepts

A nonclinical study is a scientific experiment, typically involving animal subjects, which is intended to address certain scientific questions that are the objectives of the study.

Branch:

In a study with multiple Arms, the protocol plans for each subject to be assigned to one Arm. The time within the study at which this assignment takes place is often the point at which Arms with common Elements diverge into uncommon or nonshared Elements, and is referred to as a branch point. Many studies have a single branch point. Subjects are assigned to an Arm all at the same time. For other studies, there may be two or more branches that collectively assign a subject to individual Arms. The process that makes this assignment may be a randomization, but this is not always the case, as branch points are protocol-defined.

Element:

An Element is a basic building block in the study design. All Elements are related to the administration of planned interventions, which may involve treatment or no treatment, during a period of time. Elements for which the planned intervention does not involve treatment would include screening, washout, and recovery.

Epoch:

As part of the design of a study, the planned periods or phases of subjects' participation in the study are divided into Epochs. Each Epoch is a period of time that serves a purpose in the study as a whole. Typically, the purpose of an Epoch will be to expose subjects to a treatment, or to prepare for such a treatment period (e.g., pretreatment or screening period, wash out previous treatments) or to gather data on subjects after a treatment has ended (e.g., recovery phase). It is possible for Epochs to span multiple Elements for some or all Trial Arms present on a study. For example, there may be two sequential (but different) treatment Elements planned for a group; the sponsor might choose to include both of these in a single treatment Epoch.

Treatments:

The word "treatment" may be used in connection with Epochs or Elements, but has somewhat different meanings in each context:


Since Epochs cut across Arms, an Epoch involving treatment is a higher-level concept that may not specify anything that differs between Arms. For example, in a three-period crossover study of three doses of Compound X, each treatment Epoch is associated with Compound X, but not with a specific dose. In this case, EPOCH may be populated as "Study Treatment."
An Element may be fairly detailed. For example, for an Element representing repeated dosing, an Element treatment might specify twice-daily dosing of 100-mg/kg doses of Compound X. In this case, ELEMENT may be populated as "Study Drug 100 mg/kg Administered Twice Daily."

Trial Arm:

A Trial Arm is a planned path through the study based upon a planned sequence of Elements. This path covers the entire time of the study. Each sponsor-defined protocol group may contain subjects from several Arms, one Arm, or part of an Arm. Each subject is assigned to one and only one planned Arm.

Trial Design:

The design of a study is a plan outlining the activities subjects will experience and what data will be collected during the course of the study in order to address the study's objectives.

Trial Group:

A group describes the sponsor-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 one or more Trial Sets.

Trial Set:

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 (such as diet restriction), treatment parameters, and/or sponsor-defined attributes (such as control group designation). There should be no planned parameters of interest that could further subdivide a Trial Set. Each subject must be assigned to one and only one Trial Set. Each Trial Set should be assigned to a single Group. Each Set should be assigned to a single Trial Arm.

Trial Summary:

As part of the Trial Design datasets, Trial Summary provides important or key study-level information.


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