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Permuted block randomization

In IWRS, you can diversify between two randomization methods—permuted block and dynamic. This section explains the specifics and details of the configuration and management of the permuted block (PB) randomization method.

The permuted block (PB) method involves the preparation of a randomization list before initiating the randomization process for a specific cohort. According to this method, the subjects of the specific cohort are first divided into blocks according to preset stratification factors, and then they are allocated to arms according to specific ratios. The randomization process is held by the system according to the predefined scheme—a plan according to which subjects enrolled in a study are randomized and receive treatment.

For the PB randomization scheme, the IWRS configuration process involves the following activities:

All the PB randomization schemes that you have previously added to your cohort can be found under the Randomization List module of your cohort.

PB randomization list
Figure 1. PB randomization list

The permuted block randomization schemes have the attributes explained in the following table.

Column

Details

Randomization Name

Represents the randomization scheme name.

Type

Represents the type of the randomization scheme. It can be either System Generate or Manual Upload.

Method

Represents the method of the randomization scheme. It can be either Block, Stratified, Block Stratified, or Complete.

Stratified by Sites

Represents whether the randomization scheme has been created with the Stratified by Sites option enabled. When this option is enabled, the site is automatically used as the stratified factor with the highest priority.

Stratification Strategy

Represents the stratification strategy of the randomization scheme:

  • Hierarchical: for this strategy, the stratification factors are arranged in hierarchical levels.

  • Parallel: for this strategy, the stratification factors are considered as parallel equipollent values.

Used

Represents the number of randomization IDs used.

Unused

Represents the number of randomization IDs that are not used.

Status

Represents the status of the randomization scheme and provides an option to change the status. The randomization scheme statuses can be as follows.

  • Draft: this is the default status of the added scheme. The schemes with such statuses can be modified in terms of configurations or deleted.

  • Ongoing: the status represents that the ongoing scheme is currently used for randomization. The schemes with such statuses cannot be modified or deleted.

  • Completed: the status represents that the study for which this randomization has been created is over. The schemes with such statuses can be modified or deleted if no subjects are randomized according to them.

  • Terminated: the status represents that the randomization scheme is terminated. The schemes with such statuses can be modified or deleted if no subjects are randomized according to them.

  • Suspended: the status represents that the randomization scheme is suspended. The schemes with such statuses can be modified or deleted if no subjects are randomized according to them.

  • Closed: the status represents that the randomization scheme is closed as it is no longer needed for some reason. The schemes with such statuses can be modified or deleted if no subjects are randomized according to them.

Status Change Reason

Represents the reason for changing the scheme’s status.

For instance, the randomization status has been changed to Suspended, and the reason for it can be: "One of the factors reached its upper limit".
See also
In this section:

A process during which subjects receive their random numbers and are assigned to different arms based on the randomization scheme.

A group of subjects who share a set of specific factors (characteristics) that is first defined and composed, then studied or tracked over a given time period. In a clinical trial, outlining the study cohort begins with clearly defined, study-specific inclusion criteria.

In IWRS, a variable that is used to divide a group of subjects into subgroups according to certain factors (demographic, clinical, and others).

A group of subjects formed as a result of randomization for blinding purposes that has its own schedule of visits and treatment plan according to a study protocol.

value