Times to the first recurrence of a bladder tumour, in months, for 86 patients in a placebo-controlled trial of thiotepa (Collett, 2023, Appendix B.2).
Format
A data frame with 86 rows and 6 variables:
- patient
Patient number (1-86).
- time
Time to first recurrence, in months.
- status
Event indicator: 1 = recurrence, 0 = right-censored.
- treat
Treatment: 1 = placebo, 2 = thiotepa.
- init
Initial number of tumours.
- size
Diameter of the largest initial tumour, in cm.
Source
Collett, D. (2023) Modelling Survival Data in Medical Research, 4th ed. Chapman & Hall/CRC, Appendix B.2 (Table B.2). Data from Andrews and Herzberg (1985).
Details
The trial was conducted by the Veterans Administration Cooperative Urological Research Group. Superficial tumours were removed transurethrally before randomisation. The original data set in Andrews and Herzberg (1985) contains the times to up to nine recurrences; the file here keeps only the time to the first recurrence (47 recurrences).
The appendix suggests a Cox model for init and size, an assessment of the
treatment effect after adjustment, a test of interaction, model-checking
diagnostics, a test of proportional hazards for treatment using a
time-dependent variable, and a comparison with a Weibull proportional
hazards model.
Aliases
This data set is not used in a numbered example, so it has no dX.Y alias.
See dataset_by_exercise for the complete index.
Examples
# Collett (2023), Appendix B.2 (no numbered example) ------------------
# Chapter 17 style: Cox model for the time to the first recurrence
survival::coxph(
survival::Surv(time, status) ~ init + size + factor(treat),
data = bladder
)
#> Call:
#> survival::coxph(formula = survival::Surv(time, status) ~ init +
#> size + factor(treat), data = bladder)
#>
#> coef exp(coef) se(coef) z p
#> init 0.23818 1.26894 0.07588 3.139 0.0017
#> size 0.06961 1.07209 0.10156 0.685 0.4931
#> factor(treat)2 -0.52598 0.59097 0.31583 -1.665 0.0958
#>
#> Likelihood ratio test=9.92 on 3 df, p=0.01927
#> n= 86, number of events= 47
# Modern tools --------------------------------------------------------
if (requireNamespace("broom", quietly = TRUE)) {
broom::tidy(
survival::coxph(
survival::Surv(time, status) ~ init + size + factor(treat),
data = bladder
),
exponentiate = TRUE, conf.int = TRUE
)
}
#> # A tibble: 3 × 7
#> term estimate std.error statistic p.value conf.low conf.high
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 init 1.27 0.0759 3.14 0.00170 1.09 1.47
#> 2 size 1.07 0.102 0.685 0.493 0.879 1.31
#> 3 factor(treat)2 0.591 0.316 -1.67 0.0958 0.318 1.10