Integration Point: Dropout

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Description

The Dropout integration point allows you to customize the behavior of dropouts in a longitudinal study design using a custom R script. Instead of relying on the built-in default distribution, you can implement dropout distributions such as Poisson or Weibull, to better suit your trial’s requirements.

Availability

East Horizon Explore

This integration point is available in East Horizon Explore for the following study objectives and endpoint types:

Two Arm Confirmatory: continuous, continuous with repeated measures, binary, and time-to-event outcomes.
Two Arm Confirmatory: dual time-to-event/time-to-event, dual time-to-event/binary outcomes. Coming soon
Multiple Arm Confirmatory: continuous and binary outcomes. Coming soon

East Horizon Design Coming soon

This integration point will be available in East Horizon Design in the future.

East

This integration point is available in East for the following tests (click to expand/collapse):

Design, Continuous Endpoint
- Two-Sample Test, Parallel Design, Difference of Means (MN-2S-DI)
Design, Discrete Endpoint
- Two-Sample Test, Parallel Design
  - Difference of Proportions (PN-2S-DI)
  - Ratio of Proportions (PN-2S-RA)
  - Odds Ratio of Proportions (PN-2S-OR)
- Many-Sample Test
  - Single Arm Design, Chi-Square for Specified Proportions in C Categories (PN-ns-CH1C)
  - Parallel Design, Two Group Chi-Square for Specified Proportions in C Categories (PN-ns-CH2C)
Design, Survival Endpoint
- Two-Sample Test, Parallel Design
  - Logrank Given Accrual Duration and Accrual Rates (SU-2S-LRAR)
  - Logrank Given Accrual Duration and Study Duration (SU-2S-LRSD)

Instructions

In East Horizon Explore

You can set up a dropout function in East Horizon Explore under Dropout Distribution in a Response Card while creating or editing an Input Set. For a Time-to-Event outcome or a Continuous outome with Repeated Measures, it will be under Distribution in the Dropout Rate tab of the Response Card.

Follow these steps (click to expand/collapse):

Select User Specified-R from the dropdown in the Dropout Distribution or Distribution field in the Response Card.
Browse and select the appropriate R file (filename.r) from your computer, or use the built-in R Code Assistant to create one. This file should contain function(s) written to perform various tasks to be used throughout your Project.
Choose the appropriate function name. If the expected function is not displaying, then check your R code for errors.
Set any required user parameters (variables) as needed for your function using + Add Variables.
Continue creating your project.

For a visual guide of where to find the option, refer to the screenshots below:

![]](dropout2.png)

In East

You can set up a dropout function in East by navigating to the Generate Dropout Information task of the User Defined R Function tab of a Simulation Input window, after including the option.

Follow these steps (click to expand/collapse):

Choose the appropriate test in the Design tab.
In the Design Input window, click on the Include Options button on the top right corner and select Accrual / Dropouts.
In the Accrual / Dropouts tap of the Design Input window, input values in the Response Lag and Probability of Dropout fields. To use a custom R script, these fields cannot be blank.
Compute the scenario using the Compute button, save the design using the Save in Workbook button, then navigate to the Simulation Input window by clicking on the Simulate Design button under Library.
Click on the Include Options button on the top right corner of the Simulation Input window and select both Accrual / Dropouts and User Defined R Function.
In the tab User Defined R Function, a list of tasks will appear. Place your cursor in the File Name field for the task Generate Dropout Information.
Click on the button Browse… to select the appropriate R file (filename.r) from your computer. This file should contain function(s) written to perform various tasks to be used throughout your Project.
Specify the function name you want to initialize. To copy the function’s name from the R script, click on the button View.
Set any required user parameters (variables) as needed for your function using the button Add/Edit Variables.
Continue setting up your project.

For a visual guide of where to find the option, refer to the screenshot below:

Endpoint Types

The input variables, expected output variables, examples, and templates for this integration point depend on the endpoint type (or outcome) you are using. Refer to the relevant pages below:

Continuous (Normal) Outcome

Time-to-Event (Survival) Outcome

Continuous (Normal) Outcome with Repeated Measures

Binary Outcome

Gabriel Potvin

January 16, 2025