library(survival)

cox_mod <- coxph(Surv(start, stop, event) ~ age + year + surgery + transplant, data =  heart)
summary(cox_mod)

## Call:
## coxph(formula = Surv(start, stop, event) ~ age + year + surgery + 
##     transplant, data = heart)
## 
##   n= 172, number of events= 75 
## 
##                 coef exp(coef) se …

library(survival)

head(heart)

##   start stop event        age      year surgery transplant id
## 1     0   50     1 -17.155373 0.1232033       0          0  1
## 2     0    6     1   3.835729 0.2546201       0          0  2
## 3     0    1     0   6.297057 0.2655715       0          0  3 …