#load libraries
library(Publish)
library(survival)
library(data.table)
data(traceR) #get dataframe traceR
setDT(traceR)
traceR[,':='(wmi2=factor(wallMotionIndex<0.9,levels=c(TRUE,FALSE),
labels=c("bad","good")),
abd2=factor(abdominalCircumference<95, levels=c(TRUE,FALSE),
labels=c("slim","fat")))]
traceR[,sex:=as.factor(sex)] # all subgroup variables needs to be factor
traceR[observationTime==0,observationTime:=1]
# univariate analysis of smoking in subgroups of age and sex
# Basic model from randomised study - but observed for 12 years
fit_cox <- coxph(Surv(observationTime,dead)~treatment,data=traceR)
sub_cox <- subgroupAnalysis(fit_cox,traceR,treatment="treatment",
subgroup=c("smoking","sex","wmi2","abd2")) # subgroups as character string
summary(sub_cox)
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