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Integration Point: Dropout - Continuous or Binary Outcome, Multiple Arm

Gabriel Potvin

January 16, 2025

IntegrationPointDropoutContinuousOrBinaryMultipleArm.Rmd

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Input Variables

When creating a custom R script, you can optionally use specific variables provided by East Horizon’s engine itself. These variables are automatically available and do not need to be set by the user, except for the UserParam variable. Refer to the table below for the variables that are available for this integration point, outcome, and study objective.

Variable Type Description
NumSub Integer Number of subjects in the trial.
NumArm Integer Number of arms in the trial ﴾including placebo/control, and experimental﴿.
ProbDrop Vector of Numeric Vector of length NumArm, indicating the probability of dropout for each arm. The first element corresponds to the control group, followed by the probabilities for each experimental arm in sequence.
TreatmentID Vector of Integer Vector of length NumSub, indicating the allocation of subjects to arms. Index 0 represents placebo/control. For example, [0, 0, 1] indicates three subjects: two in the control group and one experimental.
UserParam List Contains all user-defined parameters specified in the East Horizon interface (refer to the Instructions section). To access these parameters in your R code, use the syntax: UserParam$NameOfTheVariable, replacing NameOfTheVariable with the appropriate parameter name.

Expected Output Variable

East Horizon expects an output of a specific type. Refer to the table below for the expected output for this integration point:

Type Description
List A named list containing CensorInd and ErrorCode.

Expected Members of the Output List

Members Type Description
CensorInd Vector of Integer Vector of length NumSub, containing the generated censor indicator values for all subjects:
– 0: Dropout
– 1: Completer.
ErrorCode Integer Optional. Can be used to handle errors in your script:
– 0: No error.
– Positive Integer: Nonfatal error, the current simulation will be aborted, but the next simulation will proceed.
– Negative Integer: Fatal error, no further simulations will be attempted.

Minimal Template

Your R script could contain a function such as this one, with a name of your choice. All input variables must be declared, even if they are not used in the script. We recommend always declaring UserParam as a default NULL value in the function arguments, as this will ensure that the same function will work regardless of whether the user has specified any custom parameters in East Horizon.

GenCensorInd <- function( NumSub, NumArm, ProbDrop, TreatmentID, UserParam = NULL )
{
  nError                <- 0 # Error handling (no error)
  vCensoringIndicator   <- rep( 1, NumSub ) # Initializing vector to 1 (all patients are completers)    
  
  # Write the actual code here.
  # Store the generated censor indicator values in a vector called vCensoringIndicator

  return( list( CensorInd = as.integer( vPatientOutcome ), ErrorCode = as.integer( nError ) ) )
}

Examples

Explore the following examples for more context:

  1. 2-Arm, Single Endpoint - Simulate Patient Dropout
    • This example focuses on a Two-Arm Confirmatory study objective but can still provide valuable insights.