Randomization

The randomization in SMART-TRIAL uses block randomization with random block sizes.

The pseudorandom number generator is from https://www.npmjs.com/package/seedrandom using ARC4 with RC4-drop(256). The blocks sizes are 1-5 * NumberOfTrialGroups.

You need to enable and activate the randomization add-on function in the study builder, to use the randomization function. This can either be done when creating the study but also later by clicking on the “Edit Study” button in the study overview.

whitel

To define randomization for your study, go to processes and click on “+ New process” or edit an already existing process. You can find randomization under the Advanced Options in your process.

adra

Click on the "randomization" button and specify your target inclusion.

Target inclusion

Target inclusion (TI) is the TOTAL number of desired subjects in your study and is always split evenly between the number of trial groups, e.g if you have two groups and want 50 in each group, the target inclusion is 100. The randomization IDs generated are numbers between 1 and Target Inclusion, currently, it is not possible to customize randomization ID. The system will aim to generate as close to your target inclusion as possible, but requires your target inclusion is divisible with your number of trial groups, e.g. TI = 150, Number of groups = 3.

Site as a factor

The randomization must either stratify by sites or ignore sites.

If sites are used as a factor (stratifying by sites), it will create a randomization list PER site, from where the site pulls randomization records.

If sites are ignored, it will generate a central randomization list, from where each site then pulls randomization records.

Stratification by question

You can add stratification to your randomization, thereby segmenting the study population into strata. For information on stratification within clinical trials in general, please see:https://www.sciencedirect.com/science/article/pii/S0895435698001383?casa_token=ivePL7zL3g0AAAAA:a5JDzPuqInl7Gherwp-TYiTZpHQHOvZ1LC6PZdg4U_dd3477SQCKOWtB8QhroDDN82ZcAncWPsI 

In SMART-TRIAL you have the option of selecting possibility questions (multiple-choice, Yes/No) and use them for stratification in your study. 

All of the question possibilities will be used to generate strata, and if multiple questions are used the strata will be equal to the product of possibilities.

E.g.: If you have set up a stratification with a Yes/No question (smoker?), there will be two strata: Yes &  No

If you then add a multiple choice question with three possibilities ( Blood pressure: low, middle, high) it will result in six (2 x 3) combinations:

Yes | Low

Yes | Middle

Yes | High

No | Low

No | Middle

No | High

The chosen target inclusion will be split evenly between strata. Please see examples at the bottom.

Target inclusion can be increased during amendment mode, in case more randomization records are needed. It will split the additional records the same way as then the study was started. The difference between the old target inclusion and the new target inclusion will be created. E.g. Old = 200, new = 400, a total of 200 new randomization records will be created.

Randomization groups

Subsequently, add your randomization groups. You can add as many groups as you want, but can not have less than two.

rand1

Select if you want the stratification to be based on a site level or if you want to ignore the sites


rand2

Add stratification by variable if wanted, select the data event and question of interest

rand3

Enabling randomization adds a "randomization event" in your data event list and you can drag it to where in the process the subject should be randomized.

It will show up as a regular data event in the site overview. To randomize the subject, click on the data event and then randomize.

rand4

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Blinding: Study personnel can be blinded in SMART-TRIAL by removing "View Randomize" permission in the collaborator section, which will remove their ability to see which group the subjects are allocated to.

Export: It is possible to export a list with an overview of all randomizations IDs and the corresponding trial group. This requires the appropriate collaborator permission “Export Randomization list” which is a study permission. 

Template text for use in articles or protocols:

Participants were randomized to either <Control> or <Intervention> by the randomization tool in SMART-TRIAL, which uses permuted block randomization with random block sizes of the size 1-5*TrialGroups. The pseudorandom number generator is from https://www.npmjs.com/package/seedrandom using ARC4 with RC4-drop(256).

Examples of how randomization records are distributed:

Central randomization with stratification

 

 

Target Inclusion

100  

Sites

Aalborg

Copenhagen

Groups

Intervention

Control

     

Use site as factor?

NO

 

Stratification(Smoker?)

Yes

No

 

CENTRAL LIST

 

Minimum rando. records assigned:

100

 
     

Intervention (I)

50

 

Control (C)

50

 
     

I: Smoke = Yes

25

 

I: Smoke = No

25

 

C: Smoke = Yes

25

 

C: Smoke = No

25

 
     
     

Site as factor, no stratification

 

 
Target Inclusion 100  

Sites

Aalborg

Copenhagen

Groups

Intervention

Control

     

Use site as factor?

Yes

 

NO Stratification

   
 

Aalborg

Copenhagen

Minimum rando. records assigned:

50

50

     

Intervention

25

25

Control

25

25

     
     

Central randomization, no stratification

 

 
Target Inclusion 100  

Sites

Aalborg

Copenhagen

Groups

Intervention

Control

     

Use site as factor?

NO

 

NO Stratification

   
 

CENTRAL LIST

 

Minimum rando. records assigned:

100

 
     

Intervention

50

 

Control

50

 

Contact sales@smart-trial.com for more information on how to use randomization in your study.