gtreatsel.sim {asd}

ASD simulation for treatment selection

Description

Function treatsel.sim runs simulations for a trial design that tests a number of experimental treatments against a single control treatment group in a seamless adaptive trial. Test treatments are compared to the control treatment using Dunnett's many-to-one testing procedure. An interim analysis is undertaken using an early outcome measure for each treatment (and control). A decision is made on which of the treatments to take forward, using a pre-defined selection rule. Data are simulated for the final outcome measure, and data from the interim and final analyses for the final outcome measure are combined together using either the inverse normal or Fisher combination test, and hypotheses tested at the selected level. This function should not generally be called by the user. The more user-friendly function treatsel.sim covers most common applications.

Usage

gtreatsel.sim(z1=c(0,0,0),z2=c(0,0,0),zearly=c(0,0,0),v1=c(1,1,1,1),
           v2=c(1,1,1,1),vearly=c(1,1,1,1),corr=0,weight=0.5,
           nsim=1000,seed=12345678,select=0,epsilon=1,thresh=1,
           level=0.025,ptest=seq(1:length(z1)),fu=FALSE,
           method="invnorm")

Arguments

z1

Vector of test statistics for the final outcome measure based on stage 1 data

z2

Vector of test statistics for the final outcome measure based on stage 2 data

zearly

Vector of test statistics for the early outcome measure

v1

Vector of variances for the final outcome measure based on stage 1 data; in format control treatment variance followed by the test treatment variances

v2

Vector of variances for the final outcome measure based on stage 2 data; format as v1

vearly

Vector of variances for the early outcome measure; format as v1

corr

Vector of correlations between the early and final outcome measures for the control and test treatments; format as v1

weight

Weighting between stages 1 and 2; default is for equal weighting (0.5)

nsim

Number of simulations (maximum=10,000,000)

seed

Seed number

select

Selection rule type; 0 = select all treatments, 1 = select maximum, 2 = select maximum two, 3 = select maximum three, 4 = epsilon rule (select means within epsilon of maximum), 5 = randomly select a single treatment and 6 = threshold rule (select means greater than or equal to threshold). See select.rule

epsilon

For select = 4, set epsilon criterion

thresh

For select = 6, set threshold criterion

level

Test level (default=0.025)

ptest

Vector of treatment numbers for determining power; for example, c(1,2) will count rejections of one or both hypotheses for testing treatments 1 and 2 against control

fu

Logical indicating whether patients from dropped treatments (after interim selection) should be followed-up; default TRUE

method

Select combination method; available options are “invnorm” or “fisher”, with default “invnorm”

Details

A structured description of the the methodology and the simulation model is given by Friede et al. (2011) and implementation by Parsons et al. (2012).

Value

count.total

Number of times one or more treatments are selected

select.total

Number of times each test treatment is selected

reject.total

Number of times each hypothesis is rejected

sim.reject

Number of times one or more of the treatments selected using ptest is rejected

Author(s)

Nick Parsons ([e-mail])

References

Friede T, Parsons N, Stallard N, Todd S, Valdes Marquez E, Chataway J, Nicholas R. Designing a Seamless Phase II/III Clinical Trial using Early Outcomes for Treatment Selection: an Application in Multiple Sclerosis. Statistics in Medicine 2011;30:1528-1540.

Parsons N, Friede T, Todd S, Valdes Marquez E, Chataway J, Nicholas R, Stallard N. An R package for implementing simulations for seamless phase II/III clinicals trials using early outcomes for treatment selection. Computational Statistics and Data Analysis 2012;56:1150-1160.

See Also

treatsel.sim

Examples

gtreatsel.sim(z1=c(1,0,2),z2=c(1,0,2),zearly=c(1,0,1), 
    v1=c(1,1,1,1),v2=c(1,1,1,1),vearly=c(1,1,1,1), 
    corr=0,weight=0.25,nsim=100,seed=12345678,
    select=1,level=0.025,ptest = c(1:3),method="fisher")