R: Data from a trial of usrodeoxycholic acid

udca {survival} | R Documentation

## Data from a trial of usrodeoxycholic acid

### Description

Data from a trial of ursodeoxycholic acid (UDCA) in patients with primary biliary cirrohosis (PBC).

### Usage

    data("udca")

### Format

A data frame with 170 observations on the following 15 variables.

`id`

  subject identifier

`trt`

  treatment of 0=placebo, 1=UDCA

`entry.dt`

  date of entry into the study

`last.dt`

  date of last on-study visit

`stage`

  stage of disease

`bili`

  bilirubin value at entry

`riskscore`

  the Mayo PBC risk score at entry

`death.dt`

  date of death

`tx.dt`

  date of liver transplant

`hprogress.dt`

  date of histologic progression

`varices.dt`

  appearance of esphogeal varices

`ascites.dt`

  appearance of ascites

`enceph.dt`

  appearance of encephalopathy

`double.dt`

  doubling of initial bilirubin

`worsen.dt`

  worsening of symptoms by two stages

### Details

This data set is used in the Therneau and Grambsh. The `udca1` data set contains the baseline variables along with the time until the first endpoint (any of death, transplant, ..., worsening). The `udca2` data set treats all of the endpoints as parallel events and has a stratum for each.

### References

T. M. Therneau and P. M. Grambsch, Modeling survival data: extending the Cox model. Springer, 2000.

K. D. Lindor, E. R. Dickson, W. P Baldus, R.A. Jorgensen, J. Ludwig, P. A. Murtaugh, J. M. Harrison, R. H. Weisner, M. L. Anderson, S. M. Lange, G. LeSage, S. S. Rossi and A. F. Hofman. Ursodeoxycholic acid in the treatment of primary biliary cirrhosis. Gastroenterology, 106:1284-1290, 1994.

### Examples

    data(udca)
    # values found in table 8.3 of the book
    fit1 <- coxph(Surv(futime, status) ~ trt + log(bili) + stage,
              cluster =id , data=udca1)
    fit2 <- coxph(Surv(futime, status) ~ trt + log(bili) + stage +
              strata(endpoint), cluster=id,  data=udca2)

[Package survival version 3.2-7 Index]