---
title: "Two-Stage Randomization for for Competing risks and Survival outcomes"
author: Klaus Holst & Thomas Scheike
date: "`r Sys.Date()`"
output:
rmarkdown::html_vignette:
fig_caption: yes
fig_width: 7.15
fig_height: 5.5
vignette: >
%\VignetteIndexEntry{Two-Stage Randomization for for Competing risks and Survival outcomes}
%\VignetteEngine{knitr::rmarkdown}
%\VignetteEncoding{UTF-8}
---
```{r, include = FALSE}
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>"
)
library(mets)
```
Two-Stage Randomization for for Competing risks and Survival outcomes
=====================================================================
Under two-stage randomization we can estimate the average treatment effect $E(Y(i,\bar k))$ of treatment regime $(i,\bar k)$.
- treatment A0=i
and
- for all responses, randomization A1 = (k_1), so treatment k_1
- response*A1 = (k_1, k_2), so treatment k_1 if response 1, and treatment k_2 if response 2.
The estimator can be agumented in different ways: using the two randomizations and the dynamic censoring augmentatation.
Estimating $\mu_{i,\bar k} = P(Y(i,\bar k,\epsilon=v) <= t)$, restricted mean
$E( \min(Y(i,\bar k),\tau))$ or years lost $E( I(\epsilon=v) \cdot (\tau - \min(Y(i,\bar k),\tau)))$
using IPCW weighted estimating equations : \\
The solved estimating eqution is
\begin{align*}
\sum_i \frac{I(min(T_i,t) < G_i)}{G_c(min(T_i ,t))} I(T \leq t, \epsilon=1 ) - AUG_0 - AUG_1 + AUG_C - p(i,j)) = 0
\end{align*}
using the covariates from augmentR0 to augment with
\begin{align*}
AUG_0 = \frac{A_0(i) - \pi_0(i)}{ \pi_0(i)} X_0 \gamma_0
\end{align*}
and using the covariates from augmentR1 to augment with
\begin{align*}
AUG_1 = \frac{A_0(i)}{\pi_0(i)} \frac{A_1(j) - \pi_1(j)}{ \pi_1(j)} X_1 \gamma_1
\end{align*}
and censoring augmenting with
\begin{align*}
AUG_C = \int_0^t \gamma_c(s)^T (e(s) - \bar e(s)) \frac{1}{G_c(s) } dM_c(s)
\end{align*}
where $\gamma_c(s)$ is chosen to minimize the variance given the dynamic covariates specified by augmentC.
- The treatment's must be given as factors.
- Treatment for 2nd randomization may depend on response.
- Treatment probabilities are estimated by default and uncertainty from this adjusted for.
- Randomization augmentation for 1'st and 2'nd randomization possible.
- Censoring model possibly stratified on observed covariates (at time 0).
- Censoring augmentation done dynamically over time with time-dependent covariates.
Standard errors are estimated using the influence function of all estimators and tests of differences can therefore be computed
subsequently.
Data must be given on start,stop,status survival format with
- one code of status indicating response, that is 2nd randomization
- other codes defines the outcome of interest
```{r}
library(mets)
set.seed(100)
n <- 200
ddf <- mets:::gsim(n,covs=1,null=0,cens=1,ce=1,betac=c(0.3,1))
true <- apply(ddf$TTt<2,2,mean)
true
datat <- ddf$datat
## set-random response on data, only relevant after status==2
response <- rbinom(n,1,0.5)
datat$response <- as.factor(response[datat$id]*datat$Count2)
datat$A000 <- as.factor(1)
datat$A111 <- as.factor(1)
bb <- binregTSR(Event(entry,time,status)~+1+cluster(id),datat,time=2,cause=c(1),response.code=2,
treat.model0=A0.f~+1, treat.model1=A1.f~A0.f,
augmentR1=~X11+X12+TR, augmentR0=~X01+X02,
augmentC=~X01+X02+A11t+A12t+X11+X12+TR, cens.model=~strata(A0.f))
bb
estimate(coef=bb$riskG$riskG01[,1],vcov=crossprod(bb$riskG.iid$riskG01))
estimate(coef=bb$riskG$riskG01[,1],vcov=crossprod(bb$riskG.iid$riskG01),f=function(p) c(p[1]/p[2],p[3]/p[4]))
estimate(coef=bb$riskG$riskG01[,1],vcov=crossprod(bb$riskG.iid$riskG01),f=function(p) c(p[1]-p[2],p[3]-p[4]))
```
```{r}
## 2 levels for each response , fixed weights
datat$response.f <- as.factor(datat$response)
bb <- binregTSR(Event(entry,time,status)~+1+cluster(id),datat,time=2,cause=c(1),response.code=2,
treat.model0=A0.f~+1, treat.model1=A1.f~A0.f*response.f,
augmentR0=~X01+X02, augmentR1=~X11+X12,
augmentC=~X01+X02+A11t+A12t+X11+X12+TR, cens.model=~strata(A0.f),
estpr=c(0,0),pi0=0.5,pi1=0.5)
bb
## 2 levels for each response , estimated treat probabilities
bb <- binregTSR(Event(entry,time,status)~+1+cluster(id),datat,time=2,cause=c(1),response.code=2,
treat.model0=A0.f~+1, treat.model1=A1.f~A0.f*response.f,
augmentR0=~X01+X02, augmentR1=~X11+X12,
augmentC=~X01+X02+A11t+A12t+X11+X12+TR, cens.model=~strata(A0.f),estpr=c(1,1))
bb
## 2 and 3 levels for each response , fixed weights
datat$A1.23.f <- as.numeric(datat$A1.f)
dtable(datat,~A1.23.f+response)
datat <- dtransform(datat,A1.23.f=2+rbinom(nrow(datat),1,0.5),
Count2==1 & A1.23.f==2 & response==0)
dtable(datat,~A1.23.f+response)
datat$A1.23.f <- as.factor(datat$A1.23.f)
dtable(datat,~A1.23.f+response|Count2==1)
###
bb <- binregTSR(Event(entry,time,status)~+1+cluster(id),datat,time=2,cause=c(1),response.code=2,
treat.model0=A0.f~+1, treat.model1=A1.23.f~A0.f*response.f,
augmentR0=~X01+X02, augmentR1=~X11+X12,
augmentC=~X01+X02+A11t+A12t+X11+X12+TR, cens.model=~strata(A0.f),
estpr=c(1,0),pi1=c(0.3,0.5))
bb
## 2 and 3 levels for each response , estimated
bb <- binregTSR(Event(entry,time,status)~+1+cluster(id),datat,time=2,cause=c(1),response.code=2,
treat.model0=A0.f~+1, treat.model1=A1.23.f~A0.f*response.f,
augmentR0=~X01+X02, augmentR1=~X11+X12,
augmentC=~X01+X02+A11t+A12t+X11+X12+TR, cens.model=~strata(A0.f),estpr=c(1,1))
bb
## 2 and 1 level for each response
datat$A1.21.f <- as.numeric(datat$A1.f)
dtable(datat,~A1.21.f+response|Count2==1)
datat <- dtransform(datat,A1.21.f=1,Count2==1 & response==1)
dtable(datat,~A1.21.f+response|Count2==1)
datat$A1.21.f <- as.factor(datat$A1.21.f)
dtable(datat,~A1.21.f+response|Count2==1)
bb <- binregTSR(Event(entry,time,status)~+1+cluster(id),datat,time=2,cause=c(1),response.code=2,
treat.model0=A0.f~+1, treat.model1=A1.21.f~A0.f*response.f,
augmentR0=~X01+X02, augmentR1=~X11+X12,
augmentC=~X01+X02+A11t+A12t+X11+X12+TR, cens.model=~strata(A0.f),estpr=c(1,1))
bb
## known weights
bb <- binregTSR(Event(entry,time,status)~+1+cluster(id),datat,time=2,cause=c(1),response.code=2,
treat.model0=A0.f~+1, treat.model1=A1.21.f~A0.f*response.f,
augmentR0=~X01+X02, augmentR1=~X11+X12,
augmentC=~X01+X02+A11t+A12t+X11+X12+TR, cens.model=~strata(A0.f),estpr=c(1,0),pi1=c(0.5,1))
bb
```
Two-Stage Randomization CALGB-9823
==================================
We here illustrate some analysis of one SMART conducted by Cancer and
Leukemia Group B Protocol 8923 (CALGB 8923), Stone and others (2001).
388 patients were randomized to an initial treatment of GM-CSF (A1 ) or standard chemotherapy
(A2 ). Patients with complete remission and informed consent to second stage were then re-randomized to
only cytarabine (B1 ) or cytarabine plus mitoxantrone (B2 ).
We first compute the weighted risk-set estimator based on estimated weights
\begin{align*}
\Lambda_{A1,B1}(t) & = \sum_i \int_0^t \frac{w_i(s)}{Y^w(s)} dN_i(s)
\end{align*}
where $w_i(s) = I(A0_i=A1) + (t>T_R) I(A1_i=B1)/\pi_1(X_i)$, that is
1 when you start on treatment $A1$ and
then for those that changes to $B1$ at time $T_R$ then is scaled up
with the proportion doing this. This is equivalent to
the IPTW (inverse probability of treatment weighted estimator). We estimate
the treatment regimes $A1, B1$ and $A2, B1$ by letting $A10$ indicate those that are consistent with ending on $B1$.
$A10$ then starts being $1$ and becomes $0$ if the subject is treated with $B2$, but stays $1$ if the subject is treated with $B1$.
We can then look at the two strata where $A0=0,A10=1$ and $A0=1,A10=1$. Similary, for those that end being consistent with $B2$.
Thus defining $A11$ to start being $1$, then stays $1$ if $B2$ is taken, and becomes $0$ if the second randomization is $B1$.
- the treatment models are for all time-points, unless the weight.var variable is given (1 for treatments, 0 otherwise) to accomodate a general start,stop format
- the treatment model may also depend on a response value
- standard errors are based on influence functions and is also computed for the baseline
We here use the propensity score model $P(A1=B1|A0)$ that uses the
observed frequencies on arm $B1$ among those starting out on either $A1$ or $A2$.
```{r}
data(calgb8923)
calgt <- calgb8923
tm=At.f~factor(Count2)+age+sex+wbc
tm=At.f~factor(Count2)
tm=At.f~factor(Count2)*A0.f
head(calgt)
ll0 <- phreg_IPTW(Event(start,time,status==1)~strata(A0,A10)+cluster(id),calgt,treat.model=tm)
pll0 <- predict(ll0,expand.grid(A0=0:1,A10=0,id=1))
ll1 <- phreg_IPTW(Event(start,time,status==1)~strata(A0,A11)+cluster(id),calgt,treat.model=tm)
pll1 <- predict(ll1,expand.grid(A0=0:1,A11=1,id=1))
plot(pll0,se=1,lwd=2,col=1:2,lty=1,xlab="time (months)",xlim=c(0,30))
plot(pll1,add=TRUE,col=3:4,se=1,lwd=2,lty=1,xlim=c(0,30))
abline(h=0.25)
legend("topright",c("A1B1","A2B1","A1B2","A2B2"),col=c(1,2,3,4),lty=1)
summary(pll1,times=12)
summary(pll0,times=12)
```
The propensity score mode can be extended to use covariates to get increased efficiency.
Note also that the propensity scores for $A0$ will cancel out in the different strata.
SessionInfo
============
```{r}
sessionInfo()
```