# Getting started with rpact

#### Friedrich Pahlke and Gernot Wassmer

#### 2026-03-04

Confirmatory Adaptive Clinical Trial Design, Simulation, and Analysis

## Functional Range

- Fixed sample design and designs with interim analysis stages
- Sample size and power calculation for
  - means (continuous endpoint)
  - rates (binary endpoint)
  - survival trials with flexible recruitment and survival time options
  - count data
- Simulation tool for means, rates, survival data, and count data
  - Assessment of adaptive sample size/event number recalculations based on conditional power
  - Assessment of treatment selection strategies in multi-arm trials
- Adaptive analysis of means, rates, and survival data
- Adaptive designs and analysis for multi-arm trials
- Adaptive analysis and simulation tools for enrichment design testing means, rates, and hazard ratios
- Automatic boundary recalculations during the trial for analysis with alpha spending approach, including under- and over-running

## Learn to use rpact

We recommend three ways to learn how to use `rpact`:

> 1. Use RPACT Cloud: rpact.cloud
> 2. Use the Vignettes: rpact.org/vignettes
> 3. Book a training: rpact.com

### RPACT Cloud

A graphical user interface (GUI) for the rpact R package, designed to simplify its use through an intuitive interface: rpact.cloud

### Vignettes

Developed for practical use: our collection of practical examples and use-cases, the so-called rpact vignettes, are hosted at rpact.org/vignettes

## User Concept

### Workflow

- Everything is starting with a design, e.g.: `design <- getDesignGroupSequential()`
- Find the optimal design parameters with help of rpact comparison tools: `getDesignSet`
- Calculate the required sample size, e.g.: `getSampleSizeMeans()`, `getPowerMeans()`
- Simulate specific characteristics of an adaptive design, e.g.: `getSimulationMeans()`
- Collect your data, import it into R and create a dataset: `data <- getDataset()`
- Analyze your data: `getAnalysisResults(design, data)`

### Focus on Usability

The most important rpact functions have intuitive names:

- `getDesign`[`GroupSequential`/`InverseNormal`/`Fisher`]`()`
- `getDesignCharacteristics()`
- `getSampleSize`[`Means`/`Rates`/`Survival`/`Counts`]`()`
- `getPower`[`Means`/`Rates`/`Survival`/`Counts`]`()`
- `getSimulation`[`MultiArm`/`Enrichment`][`Means`/`Rates`/`Survival`/`Counts`]`()`
- `getDataset()`
- `getAnalysisResults()`
- `getStageResults()`

RStudio / Positron / Eclipse: auto code completion makes it easy to use these functions.

### R generics

In general, everything runs with the R standard functions which are always present in R: so-called R generics, e.g., `print`, `summary`, `plot`, `as.data.frame`, `names`, `length`

### Utilities

Several utility functions are available, e.g.

- `getAccrualTime()`
- `getPiecewiseSurvivalTime()`
- `getNumberOfSubjects()`
- `getEventProbabilities()`
- `getPiecewiseExponentialDistribution()`
- survival helper functions for conversion of `pi`, `lambda` and `median`, e.g., `getLambdaByMedian()`
- `testPackage()`: installation qualification on a client computer or company server (see Installation Qualification of rpact)

## Validation

Please contact us to learn how to use `rpact` on FDA/GxP-compliant validated corporate computer systems and how to get a copy of the formal validation documentation that is customized and licensed for exclusive use by your company, e.g., to fulfill regulatory requirements.

## RPACT Connect

Connecting you to insights, downloads, and premium support: connect.rpact.com

## About

- rpact is a comprehensive validated1 R package for clinical research which
  - enables the design and analysis of confirmatory adaptive group sequential designs
  - is a powerful sample size calculator
  - is a free of charge open-source software licensed under LGPL-3
  - particularly, implements the methods described in the recent monograph by Wassmer and Brannath (2025)

> For more information please visit rpact.org

- RPACT is a company which offers
  - enterprise software development services
  - technical support for the `rpact` package
  - consultancy and user training for clinical research using R
  - validated software solutions and R package development for clinical research

> For more information please visit rpact.com

## Contact

- info@rpact.com
- rpact.com/contact

1. The rpact validation documentation is available exclusively for our customers and supporting companies. For more information visit rpact.com/services/service-level-agreement↩︎