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https://github.com/kkholst/mets

Analysis of Multivariate Event Times https://kkholst.github.io/mets/
https://github.com/kkholst/mets

multivariate-time-to-event r survival-analysis time-to-event

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Analysis of Multivariate Event Times https://kkholst.github.io/mets/

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# Multivariate Event Times (`mets`)

Implementation of various statistical models for multivariate
event history data . Including multivariate
cumulative incidence models , and bivariate random
effects probit models (Liability models) .
Modern methods for survival analysis, including regression modelling (Cox, Fine-Gray,
Ghosh-Lin, Binomial regression) with fast computation of influence functions.
Restricted mean survival time regression and years lost for competing risks.
Average treatment effects and G-computation.

## Installation

```r
install.packages("mets")
```

The development version may be installed directly from github
(requires [Rtools](https://cran.r-project.org/bin/windows/Rtools/) on windows and [development tools](https://cran.r-project.org/bin/macosx/tools/) (+Xcode) for Mac OS
X):

```r
remotes::install_github("kkholst/mets", dependencies="Suggests")
```

or to get development version

```r
remotes::install_github("kkholst/mets",ref="develop")
```

## Citation

To cite the `mets` package please use one of the following references

> Thomas H. Scheike and Klaus K. Holst and Jacob B. Hjelmborg (2013).
> Estimating heritability for cause specific mortality based on twin studies.
> Lifetime Data Analysis.

> Klaus K. Holst and Thomas H. Scheike Jacob B. Hjelmborg (2015).
> The Liability Threshold Model for Censored Twin Data.
> Computational Statistics and Data Analysis.

BibTeX:

@Article{,
title={Estimating heritability for cause specific mortality based on twin studies},
author={Scheike, Thomas H. and Holst, Klaus K. and Hjelmborg, Jacob B.},
year={2013},
issn={1380-7870},
journal={Lifetime Data Analysis},
doi={10.1007/s10985-013-9244-x},
url={http://dx.doi.org/10.1007/s10985-013-9244-x},
publisher={Springer US},
keywords={Cause specific hazards; Competing risks; Delayed entry;
Left truncation; Heritability; Survival analysis},
pages={1-24},
language={English}
}

@Article{,
title={The Liability Threshold Model for Censored Twin Data},
author={Holst, Klaus K. and Scheike, Thomas H. and Hjelmborg, Jacob B.},
year={2015},
doi={10.1016/j.csda.2015.01.014},
url={http://dx.doi.org/10.1016/j.csda.2015.01.014},
journal={Computational Statistics and Data Analysis}
}

## Examples: Twins Polygenic modelling

First considering standard twin modelling (ACE, AE, ADE, and more models)

```r
ace <- twinlm(y ~ 1, data=d, DZ="DZ", zyg="zyg", id="id")
ace
## An AE-model could be fitted as
ae <- twinlm(y ~ 1, data=d, DZ="DZ", zyg="zyg", id="id", type="ae")
## LRT:
lava::compare(ae,ace)
## AIC
AIC(ae)-AIC(ace)
## To adjust for the covariates we simply alter the formula statement
ace2 <- twinlm(y ~ x1+x2, data=d, DZ="DZ", zyg="zyg", id="id", type="ace")
## Summary/GOF
summary(ace2)
```

## Examples: Twins Polygenic modelling time-to-events Data

In the context of time-to-events data we consider the
"Liabilty Threshold model" with IPCW adjustment for censoring.

First we fit the bivariate probit model (same marginals in MZ and DZ twins but
different correlation parameter). Here we evaluate the risk of getting
cancer before the last double cancer event (95 years)

```{r}
data(prt)
prt0 <- force.same.cens(prt, cause="status", cens.code=0, time="time", id="id")
prt0$country <- relevel(prt0$country, ref="Sweden")
prt_wide <- fast.reshape(prt0, id="id", num="num", varying=c("time","status","cancer"))
prt_time <- subset(prt_wide, cancer1 & cancer2, select=c(time1, time2, zyg))
tau <- 95
tt <- seq(70, tau, length.out=5) ## Time points to evaluate model in

b0 <- bptwin.time(cancer ~ 1, data=prt0, id="id", zyg="zyg", DZ="DZ", type="cor",
cens.formula=Surv(time,status==0)~zyg, breaks=tau)
summary(b0)
```

Liability threshold model with ACE random effects structure

```{r, label=liability_ace1, eval=fullVignette}
b1 <- bptwin.time(cancer ~ 1, data=prt0, id="id", zyg="zyg", DZ="DZ", type="ace",
cens.formula=Surv(time,status==0)~zyg, breaks=tau)
summary(b1)
```

## Examples: Twins Concordance for time-to-events Data

```r

data(prt) ## Prostate data example (sim)

## Bivariate competing risk, concordance estimates
p33 <- bicomprisk(Event(time,status)~strata(zyg)+id(id),
data=prt, cause=c(2,2), return.data=1, prodlim=TRUE)

p33dz <- p33$model$"DZ"$comp.risk
p33mz <- p33$model$"MZ"$comp.risk

## Probability weights based on Aalen's additive model (same censoring within pair)
prtw <- ipw(Surv(time,status==0)~country+zyg, data=prt,
obs.only=TRUE, same.cens=TRUE,
cluster="id", weight.name="w")

## Marginal model (wrongly ignoring censorings)
bpmz <- biprobit(cancer~1 + cluster(id),
data=subset(prt,zyg=="MZ"), eqmarg=TRUE)

## Extended liability model
bpmzIPW <- biprobit(cancer~1 + cluster(id),
data=subset(prtw,zyg=="MZ"),
weights="w")
smz <- summary(bpmzIPW)

## Concordance
plot(p33mz,ylim=c(0,0.1),axes=FALSE, automar=FALSE,atrisk=FALSE,background=TRUE,background.fg="white")
axis(2); axis(1)

abline(h=smz$prob["Concordance",],lwd=c(2,1,1),col="darkblue")
## Wrong estimates:
abline(h=summary(bpmz)$prob["Concordance",],lwd=c(2,1,1),col="lightgray", lty=2)
```

plot of chunk ex1

## Examples: Cox model, RMST

We can fit the Cox model and compute many useful summaries, such as
restricted mean survival and stanardized treatment effects (G-estimation).
First estimating the standardized survival

```{r}
data(bmt); bmt$time <- bmt$time+runif(408)*0.001
bmt$event <- (bmt$cause!=0)*1
dfactor(bmt) <- tcell.f~tcell

ss <- phreg(Surv(time,event)~tcell.f+platelet+age,bmt)
summary(survivalG(ss,bmt,50))

sst <- survivalGtime(ss,bmt,n=50)
plot(sst,type=c("survival","risk","survival.ratio")[1])
```

Based on the phreg, that can be used to get the the Kaplan-Meier, we can also compute
restricted mean survival times and years lost

```{r}
out1 <- phreg(Surv(time,cause!=0)~strata(tcell,platelet),data=bmt)

rm1 <- resmean.phreg(out1,times=50)
summary(rm1)
par(mfrow=c(1,2))
plot(rm1,se=1)
plot(rm1,years.lost=TRUE,se=1)
```

and for competing risks the years lost can be decomposed into different causes

```{r}
## years.lost decomposed into causes
drm1 <- cif.yearslost(Event(time,cause)~strata(tcell,platelet),data=bmt,times=10*(1:6))
par(mfrow=c(1,2)); plot(drm1,cause=1,se=1); plot(drm1,cause=2,se=1);
summary(drm1)
```

## Examples: Cox model IPTW

We can fit the Cox model with inverse probabilty of treatment weights based on
logistic regression. The treatment weights can be time-dependent and then mutiplicative
weights are applied.

```{r}
library(mets)
data(bmt); bmt$time <- bmt$time+runif(408)*0.001
bmt$event <- (bmt$cause!=0)*1
dfactor(bmt) <- tcell.f~tcell

ss <- phreg_IPTW(Surv(time,event)~tcell.f,data=bmt,treat.model=tcell.f~platelet+age)
summary(ss)
```

## Examples: Competing risks regression, Binomial Regression

We can fit the logistic regression model at a specific time-point with IPCW adjustment

```{r}
data(bmt); bmt$time <- bmt$time+runif(408)*0.001
# logistic regresion with IPCW binomial regression
out <- binreg(Event(time,cause)~tcell+platelet,bmt,time=50)
summary(out)

predict(out,data.frame(tcell=c(0,1),platelet=c(1,1)),se=TRUE)
```

## Examples: Competing risks regression, Fine-Gray/Logistic link

We can fit the Fine-Gray model and the logit-link competing risks model
(using IPCW adjustment). Starting with the logit-link model

```{r}
data(bmt)
bmt$time <- bmt$time+runif(nrow(bmt))*0.01
bmt$id <- 1:nrow(bmt)

## logistic link OR interpretation
or=cifreg(Event(time,cause)~strata(tcell)+platelet+age,data=bmt,cause=1)
summary(or)
par(mfrow=c(1,2))
## to see baseline
plot(or)

# predictions
nd <- data.frame(tcell=c(1,0),platelet=0,age=0)
pll <- predict(or,nd)
plot(pll)
```

Similarly, the Fine-Gray model can be estimated using IPCW adjustment

```{r}
## Fine-Gray model
fg=cifreg(Event(time,cause)~strata(tcell)+platelet+age,data=bmt,cause=1,propodds=NULL)
summary(fg)
## baselines
plot(fg)
nd <- data.frame(tcell=c(1,0),platelet=0,age=0)
pfg <- predict(fg,nd,se=1)
plot(pfg,se=1)

## influence functions of regression coefficients
head(iid(fg))
```

and we can get standard errors for predictions based on the influence functions of
the baseline and the regression coefiicients

```{r}
baseid <- IIDbaseline.cifreg(fg,time=40)
FGprediid(baseid,nd)
```

further G-estimation can be done

```{r}
dfactor(bmt) <- tcell.f~tcell
fg1 <- cifreg(Event(time,cause)~tcell.f+platelet+age,bmt,cause=1,propodds=NULL)
summary(survivalG(fg1,bmt,50))
```

## Examples: Marginal mean for recurrent events

We can estimate the expected number of events non-parametrically and
get standard errors for this estimator

```{r}
data(hfactioncpx12)
dtable(hfactioncpx12,~status)

gl1 <- recurrentMarginal(Event(entry,time,status)~strata(treatment)+cluster(id),hfactioncpx12,cause=1,death.code=2)
summary(gl1,times=1:5)
plot(gl1,se=1)
```

## Examples: Ghosh-Lin for recurrent events

We can fit the Ghosh-Lin model for the expected number of events observed
before dying (using IPCW adjustment and get predictions)

```{r}
data(hfactioncpx12)
dtable(hfactioncpx12,~status)

gl1 <- recreg(Event(entry,time,status)~treatment+cluster(id),hfactioncpx12,cause=1,death.code=2)
summary(gl1)

## influence functions of regression coefficients
head(iid(gl1))
```
and we can get standard errors for predictions based on the influence functions of the baseline
and the regression coefiicients

```{r}
nd=data.frame(treatment=levels(hfactioncpx12$treatment),id=1)
pfg <- predict(gl1,nd,se=1)
summary(pfg,times=1:5)
plot(pfg,se=1)
```

and we can get the influence functions of the baseline and regression coefficients at
a specific time-point

```{r}
baseid <- IIDbaseline.recreg(gl1,time=2)
dd <- data.frame(treatment=levels(hfactioncpx12$treatment),id=1)
GLprediid(baseid,dd)
```

## Examples: Fixed time modelling for recurrent events

We can fit a log-link regression model at 2 yeas for the expected number of events observed
before dying (using IPCW adjustment)

```{r}
data(hfactioncpx12)

e2 <- recregIPCW(Event(entry,time,status)~treatment+cluster(id),hfactioncpx12,cause=1,death.code=2,time=2)
summary(e2)
```

## Examples: Regression for RMST/Restricted mean survival for survival and competing risks using IPCW

RMST can be computed using the Kaplan-Meier (via phreg) and the for competing
risks via the cumulative incidence functions, but we can also get these
estimates via IPCW adjustment and then we can do regression

```{r}
### same as Kaplan-Meier for full censoring model
bmt$int <- with(bmt,strata(tcell,platelet))
out <- resmeanIPCW(Event(time,cause!=0)~-1+int,bmt,time=30,
cens.model=~strata(platelet,tcell),model="lin")
estimate(out)
## same as
out1 <- phreg(Surv(time,cause!=0)~strata(tcell,platelet),data=bmt)
rm1 <- resmean.phreg(out1,times=30)
summary(rm1)

## competing risks years-lost for cause 1
out1 <- resmeanIPCW(Event(time,cause)~-1+int,bmt,time=30,cause=1,
cens.model=~strata(platelet,tcell),model="lin")
estimate(out1)
## same as
drm1 <- cif.yearslost(Event(time,cause)~strata(tcell,platelet),data=bmt,times=30)
summary(drm1)
```

## Examples: Average treatment effects (ATE) for survival or competing risks

We can compute ATE for survival or competing risks data for the
probabilty of dying

```{r}
bmt$event <- bmt$cause!=0; dfactor(bmt) <- tcell~tcell
brs <- binregATE(Event(time,cause)~tcell+platelet+age,bmt,time=50,cause=1,
treat.model=tcell~platelet+age)
summary(brs)
```

or the the restricted mean survival (years-lost to different causes)

```{r}
out <- resmeanATE(Event(time,event)~tcell+platelet,data=bmt,time=40,treat.model=tcell~platelet)
summary(out)

out1 <- resmeanATE(Event(time,cause)~tcell+platelet,data=bmt,cause=1,time=40,
treat.model=tcell~platelet)
summary(out1)
```