WCRBayesDesign

Bayesian Two-Stage Adaptive Design for Single-Arm Survival Trials

Overview

WCRBayesDesign provides simulation and optimization tools for Bayesian two-stage adaptive single-arm trials with time-to-event endpoints. All statistical calculations are carried out in a transformed-time space induced by a reference survival function \(S_0\), while key results are reported on the original time scale for clinical interpretability.

Installation

# Install from source
install.packages("WCRBayesDesign_1.0.0.tar.gz", repos = NULL, type = "source")

Quick Start

library(WCRBayesDesign)

# Step 1 - Search feasible interim-analysis parameters
res_pIA <- find_Nw_pIA(
  tau = 24, theta_L = 0.62, theta_alt = 0.80,
  alpha_target = 0.05, beta_target = 0.20,
  rate = 5/12, X_grid = c(1, 2, 3),
  S0_dist = "weibull",
  S0_par = list(k = 1.2, lambda = 0.08)
)

# Step 2 - Optimise the two-stage design
opt <- two_stage_optimize_design(
  NwX_pIA_results = res_pIA,
  rate = 5/12, tau = 24,
  theta_L = 0.62, theta_alt = 0.80,
  alpha_target = 0.05, beta_target = 0.20,
  nsim = 2000,
  S0_dist = "weibull",
  S0_par = list(k = 1.2, lambda = 0.08),
  optimize = "ESS", ncores = 4
)

# Step 3 - Evaluate operating characteristics
oc <- oc_two_stage(
  N = 50, Nw = 30, X = 2,
  pIA = 0.5, pF = 0.05,
  rate = 5/12, tau = 24,
  theta_L = 0.62, theta_alt = 0.80,
  a0 = 0.01, b0 = 0.01, nsim = 5000,
  S0_dist = "weibull",
  S0_par = list(k = 1.2, lambda = 0.08)
)

Exported Functions

Function Purpose
find_Nw_pIA() Search for feasible interim-analysis parameters
two_stage_optimize_design() Optimise sample size and decision thresholds
oc_two_stage() Evaluate operating characteristics via simulation
run_two_stage_trial() Simulate a single two-stage trial
conduct() Perform Bayesian interim or final analysis
S0_weibull() Weibull reference survival function
S0_inverse() Inverse baseline survival function
delta_from_theta_goal() Convert survival-probability target to delta
stats_transformed() Compute transformed sufficient statistics

Supported Baseline Distributions

License

GPL-3

Authors