[R] COXPH TIME-DEPENDENT

[Daniel Malter]

B is the specification for time-varying covariates. Otherwise, your model
will think that each row is one independent observation that either had an
event or was censored at "time" or "total_time."

HTH,
Daniel



javier palacios wrote:
> 
> Dear R-community, 
> 
> which of the following two formats is correct? Are both correct? 
> 
> Please, consider this example: 
> 
> data table: 
> 
> Data
>    S sta time  TDC1 total_time
> A 1   0   1  48.50       1
> B 0   0   1  65.96       2
> B 1   1   2  65.08       2
> C 0   0   1  0.00        2
> C 1   1   2  0.00        2
> D 0   0   1 72.74        2
> D 1   1   2 72.52        2
> E 0   0   1 61.84         2
> E 0   1   2 60.56        2
> F 0   0   1 35.04        4
> F 0   1   2 36.97        4
> F 0   2   3 37.92        4
> F 1   3   4 39.01        4
> 
> time - time to event
> sta - starting time
> TDC - time dependent covariates
> total_time - total time at risk
> 
> option A
> 
> coxph(Surv(time,S) ~ time_dependent_covariates,
> data=data.frame(Data))
>  
> option B
> 
> coxph(Surv(sta,time,S) ~ time_dependent_covariates,
> data=data.frame(Data))
> 
> option C
> 
> coxph(Surv(total_time,S) ~ time_dependent_covariates,
> data=data.frame(Data))
> 
> 
> How can time at risk be visualized in the coxph output?
> 
> Best regards, 
> 
> Javier
> 

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