Trial Elements (TE)

A trial design domain that contains the element code that is unique for each element, the element description, and the rules for starting and ending an element.

The Trial Elements (TE) dataset contains the definitions of the elements that appear in the Trial Arms (TA) dataset. An element may appear multiple times in the TA table because it appears either (1) in multiple arms, (2) multiple times within an arm, or (3) both. However, an element will appear only once in the TE table.

Each row in the TE dataset may be thought of as representing a "unique element" in the same sense of "unique" as a CRF template page for a collecting certain type of data referred to as "unique page." For instance, a CRF might be described as containing 87 pages, but only 23 unique pages. By analogy, the trial design matrix in Example Trial 1 (see Section 7.2.1, Trial Arms) has 9 study cells, each of which contains 1 element, but the same trial design matrix contains only 5 unique elements, so the TE dataset for that trial has only 5 records.

An element is a building block for creating study cells, and an arm is composed of study cells. Or, from another point of view, an arm is composed of elements; that is, the trial design assigns subjects to arms, which comprise a sequence of steps called elements.

Trial elements represent an interval of time that serves a purpose in the trial and are associated with certain activities affecting the subject. “Week 2 to week 4” is not a valid element. A valid element has a name that describes the purpose of the element and includes a description of the activity or event that marks the subject's transition into the element as well as the conditions for leaving the element.

Both of the trials in TA Examples 1 and 2 (see Section 7.2.1, Trial Arms) are assumed to have fixed-duration elements. The wording in TESTRL is intended to separate the description of the event that starts the element into the part that would be visible to a blinded participant in the trial (e.g., "First dose of a treatment epoch") from the part that is revealed when the study is unblinded (e.g., "where dose is 5 mg"). Care must be taken in choosing these descriptions to be sure that they are arm- and epoch-neutral. For instance, in a crossover trial such as TA Example Trial 3, where an element may appear in 1 of multiple epochs, the wording must be appropriate for all possible epochs (e.g., "OPEN LABEL TREATMENT"). The SDS Team is considering adding a separate variable to the TE dataset that would hold information on the treatment that is associated with an element. This would make it clearer which elements are "treatment elements” and, therefore, which epochs contain treatment elements and thus are "treatment Epochs."