# A web application for the design of multi-arm clinical trials

## TL;DR

This paper introduces a user-friendly web application built with R Shiny that simplifies the design and sample size calculation for multi-arm clinical trials, promoting their wider adoption.

## Contribution

It provides an accessible, easy-to-use tool for designing multi-arm trials, including sample size and power calculations, which was previously lacking.

## Key findings

- The application supports various multiple comparison corrections.
- It allows calculation of sample size and arm-wise allocation ratios.
- The tool is freely accessible and requires no programming skills.

## Abstract

Multi-arm designs provide an effective means of evaluating several treatments within the same clinical trial. Given the large number of treatments now available for testing in many disease areas, it has been argued that their utilisation should increase. However, for any given clinical trial there are numerous possible multi-arm designs that could be used, and choosing between them can be a difficult task. This task is complicated further by a lack of available easy-to-use software for designing multi-arm trials. To aid the wider implementation of multi-arm clinical trial designs, we have developed a web application for sample size calculation when using a variety of popular multiple comparison corrections. Furthermore, the application supports sample size calculation to control several varieties of power, as well as the determination of optimised arm-wise allocation ratios. It is built using the Shiny package in the R programming language, is free to access on any device with an internet browser, and requires no programming knowledge to use. The application provides the core information required by statisticians and clinicians to review the operating characteristics of a chosen multi-arm clinical trial design. We hope that it will assist with the future utilisation of such designs in practice.