DTR (version 1.2)

DTR.CHR.plot: Cumulative hazard ratio/Log cumulative hazard ratio plot for dynamic treatment regimes (DTRs)

Description

This function plots the estimated cumulative hazard ratios (CHR) or the natural logarithms of the estimated CHRs between two different dynamic treatment regimes (DTRs) from sequentially randomized clinical trials using the CHR estimates proposed in Tang and Wahed (2013) [Epub ahead of print]. For simplicity, and to maintain similarity to the most common sequentially randomized clinical trials, a simple two-stage randomization design allowing two treatment options at each stage is implemented in the current version of the function.

Usage

DTR.CHR.plot(fdata, log.CHR=FALSE, confidence.interval=FALSE, xlab="Time", 
line.color=c("black", "grey30", "grey50", "grey60", "grey70", "grey80"), 
legend.position="right")

Arguments

fdata

a data frame (X, R, Z, U, delta, V) representing the full data from a simple two stage randomization design with therapies A1 and A2 available at the first stage, and B1 and B2 available at the second stage. X: first-stage indicator, X=0 if assigned to A

log.CHR

If log.CHR=FALSE (default), the estimated CHRs are plotted. If log.CHR=TRUE, the natural logarithms of estimated CHRs are plotted.

confidence.interval

If confidence.interval=FALSE (default), the 95% confidence bands are not plotted. If confidence.interval=TRUE, the 95% confidence bands are plotted as grey shadows.

xlab

label for x axis. Default is "Time".

line.color

colors for the lines. Default are "black", "grey30", "grey50", "grey60", "grey70" and "grey80" for A1B2 vs. A1B1, A2B1 vs. A1B1, A2B2 vs. A1B1, A2B1 vs. A1B2, A2B2 vs. A1B2, and A2B2 vs. A2B1 respectively.

legend.position

the position of legend: "left", "right" (default), "bottom", "top", or two-element numeric vector (e.g. c(0.6,0.9))

Details

In sequentially randomized designs, there could be more than two therapies available at each stage. For simplicity, and to maintain similarity to the most common sequentially randomized clinical trials, a simple two-stage randomization design allowing two treatment options at each stage is used in the current version of the package. In detail, patients are initially randomized to either A1 or A2 at the first stage. Based on their response status, they are then randomized to either B1 or B2 at the second stage. Therefore, there are a total of four dynamic treatment regimes (DTRs): A1B1, A1B2, A2B1, and A2B2. Based on four DTRs, six different cumulative hazard ratios (CHRs) are computed: CHR(A1B2 vs. A1B1), CHR(A2B1 vs. A1B1), CHR(A2B2 vs. A1B1), CHR(A2B1 vs. A1B2), CHR(A2B2 vs. A2B1), and CHR(A2B2 vs. A2B1). The natural logarithms of the CHRs are also computed.

References

Tang X, Wahed AS: Cumulative hazard ratio estimation for treatment regimes in sequentially randomized clinical trials. Statistics in Biosciences, 2013 [Epub ahead of print]

See Also

DTR, sim.CHR.data, updateBeta, CHR.estimator, CHR.Wald.test

Examples

require(DTR)
  
#-------Example function usage-----------
n <- 800
max.c <- 5
pi.x <- 0.5
pi.r <- 0.6
pi.z <- 0.5
gamma10 <- 1
gamma11 <- 1.5
gamma12 <- 1.2
gamma20 <- 1
gamma21 <- 1.5
gamma22 <- 1.3
alpha10 <- 0.5
alpha11 <- 0.2
alpha12 <- 0.1
alpha20 <- 0.5
alpha21 <- 0.2
alpha22 <- 0.05
beta <- c(0.5, 0.5)

set.seed(123)
fdata <- sim.CHR.data(n,max.c,pi.x,pi.r,pi.z,gamma10,gamma11,gamma12,
gamma20,gamma21,gamma22,alpha10,alpha11,alpha12,alpha20,alpha21,alpha22,beta)

# Plot CHR
DTR.CHR.plot(fdata, confidence.interval=TRUE)

# Plot log CHR
DTR.CHR.plot(fdata, log.CHR=TRUE, confidence.interval=FALSE)