survival (version 2.38-3)

transplant: Liver transplant waiting list

Description

Subjects on a liver transplant waiting list from 1990-1999, and their disposition: received a transplant, died while waiting, withdrew from the list, or censored.

Usage

data("transplant")

Details

This represents the transplant experience in a particular region, over a time period in which liver transplant became much more widely recognized as a viable treatment modality. The number of liver transplants rises over the period, but the number of subjects added to the liver transplant waiting list grew much faster. Important questions addressed by the data are the change in waiting time, who waits, and whether there was an consequent increase in deaths while on the list.

Blood type is an important consideration. Donor livers from subjects with blood type O can be used by patients with A, B, AB or 0 blood types, whereas a recipient of type B cannot accept an A or AB liver for instance. Thus type O subjects on the waiting list are at a disadvantage, since the pool of competitors is larger for type O donor livers.

This data is of historical interest but has little relevance to current practice. Liver allocation policies have evolved and now depend directly on individual patient's risk and need, assessments of which are regularly updated while a patient is on the waiting list. The overall organ shortage remains acute, however.

Examples

period <- cut(transplant$year, c(1989, 1992, 1995, 1997, 2000),
              labels=c('90-92', '93-95', '96-97', '98-99'))
pfit <- survfit(Surv(futime, event) ~ period, transplant)
pfit[,2]  #time to liver transplant
plot(pfit[,2], mark.time=FALSE, col=1:4, lwd=2, xmax=735,
       xscale=30.5, xlab="Months", ylab="Fraction transplanted",
       xaxt = 'n')
temp <- c(0, 6, 12, 18, 24)
axis(1, temp, temp)

legend(15, .35, levels(period), lty=1, col=1:4, lwd=2, bty='n')