conduct {DTEBOP2}R Documentation

Computes the hazard ratio between post- and pre-separation periods, provides the 95% Bayesian credible interval, and makes a Go/No-Go decision based on the trial data. This function is intended for interim and final analyses in two-arm survival trials with delayed treatment effects.

Description

Computes the hazard ratio between post- and pre-separation hazard rates, along with the 95% Bayesian credible interval. Based on the user-supplied survival data, the function also provides a Go/No-Go decision for interim or final analysis in two-arm survival trials with delayed treatment effects

Usage

conduct(
  data_E,
  data_C,
  median.1,
  median.2,
  gprior.E_1 = NULL,
  gprior.E_2 = NULL,
  L,
  U,
  trunc.para = c(1, 1),
  lambda,
  gamma,
  nmax,
  S_likely = (L + U)/2,
  value = FALSE
)

Arguments

data_E

A data frame containing the survival data for the experimental (treatment) arm. The first column should be the observed survival times, and the second column should be the event indicator (1 = event, 0 = censored).

data_C

A data frame containing the survival data for the control arm. The format is the same as data_E: first column for observed time, second column for status (1 = event, 0 = censored).

median.1

Numeric. The overall median survival time for the standard-of-care (SOC) arm.

median.2

Numeric. The overall median survival time for the experimental arm.

gprior.E_1

Optional. A numeric vector of length two specifying the shape and scale parameters of the inverse-gamma prior for the pre-separation mean survival time (i.e., 1/hazard rate). If NULL, the default is c(4,3/log(2)*median.1)

gprior.E_2

Optional. A numeric vector of length two specifying the shape and scale parameters of the inverse-gamma prior for the post-separation mean survival time (i.e., 1/hazard rate). If NULL, the default is c(4,6/log(2)*median.1)

L

Numeric. The lower bound of the delayed treatment effect (DTE) separation timepoint.

U

Numeric. The upper bound of the delayed treatment effect (DTE) separation timepoint.

trunc.para

Numeric vector of length two. Specifies the shape and scale parameters of the truncated Gamma prior for the DTE timepoint.

lambda

Numeric. Weighting parameter used in the posterior decision function:1-\lambda(n/N)^{\gamma}

gamma

Numeric. Exponent parameter used in the posterior decision function:1-\lambda(n/N)^{\gamma}

nmax

Integer. Maximum sample size per arm.

S_likely

Numeric. The most likely value of the DTE separation timepoint. Defaults to the midpoint of L and U

value

If TRUE, returns posterior means, 95% credible intervals, and event rates. Default is FALSE.

Value

A list with the following components:

posterior_mean

Posterior mean of the hazard ratio (post- / pre-separation).

credible_interval

95% Bayesian credible interval for the hazard ratio.

event_rates

Event rates for the experimental arm, control arm, and overall.

decision

One of the following trial decisions based on observed data:

Go

Trial proceeds to next stage.

No-Go

Trial stops early for futility.

Reject Null Hypothesis

Final analysis leads to rejecting H0.

Not Reject Null Hypothesis

Final analysis fails to reject H0.

Examples


conduct(data_E, data_C, median.1 = 2.8, median.2 = 3.5, L = 2, U = 2.5,
        trunc.para = c(1, 1), lambda = 0.95, gamma = 1, nmax = 63, S_likely = 2.3)
        

[Package DTEBOP2 version 1.0.3 Index]