[R] How does one pass arguments to a function, such as coxph, that itself is inside a function?

[Sorkin, John]

Question summary: How does one pass arguments to a function, such as coxph, that itself is inside a function.

I am trying to write a function that will allow me to call coxph using different outcome and time variables. The coxph works when the coxph is NOT contained in a larger function (which passes the outcome and time variable to  use), but does not work when coxph is contained in a  larger funciton.

My code:

fit0 <- coxph(Surv(FUtime,Death)~Age_in_years_at_A1_max+factor(Diabetes)+factor(CKD_stage)+
                                                       factor(Phase1_first),data=mydata)
summary(fit0)

this works: 

Call:
coxph(formula = Surv(FUtime, Death) ~ Age_in_years_at_A1_max + 
                            factor(Diabetes) + factor(CKD_stage) + factor(Phase1_first), 
    data = mydata)

  n= 350, number of events= 56 

                           coef exp(coef) se(coef)      z Pr(>|z|)    
Age_in_years_at_A1_max  0.04618   1.04727  0.01384  3.338 0.000845 ***
factor(Diabetes)1       0.12247   1.13029  0.28282  0.433 0.664991    
factor(CKD_stage)3     -0.28418   0.75263  0.38744 -0.733 0.463261    
factor(CKD_stage)4      0.33938   1.40407  0.36583  0.928 0.353572    
factor(CKD_stage)5      0.97121   2.64115  0.40171  2.418 0.015618 *  
factor(Phase1_first)1   0.02204   1.02229  0.29713  0.074 0.940868 

other output deleted.

But this code does not work:

doit <- function(time,outcome,data){
  fit0 <-
coxph(Surv(time,outcome)~Age_in_years_at_A1_max+factor(Diabetes)+factor(CKD_stage)+factor(Phase1_first),data=data)
  print(summary(fit0))
}
doit(FUtime,Death,mydata)

 Error in Surv(time, outcome) : object 'FUtime' not found 

I am certain I have a scoping problem, but I don't know how to solve it. 

John David Sorkin M.D., Ph.D.

Professor of Medicine

Chief, Biostatistics and Informatics

University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine

Baltimore VA Medical Center

10 North Greene Street

GRECC (BT/18/GR)

Baltimore, MD 21201-1524

(Phone) 410-605-7119

(Fax) 410-605-7913 (Please call phone number above prior to faxing)