Calculate Concordance Index (Harrell's or Uno's)

Usage

eval_cindex(time, event, S_mat, times, eval_time, method = "uno")

Arguments

time: Numeric vector of observed follow-up times.
event: Numeric vector of event indicators (1 = event, 0 = censored).
S_mat: A numeric matrix of predicted survival probabilities.
times: Numeric vector of evaluation times matching the columns of S_mat.
eval_time: Numeric. The specific time point at which to extract predictions.
method: Character. Either "harrell" or "uno". Defaults to "uno".

Value

A numeric value representing the chosen C-index.

Examples

data("metabric", package = "SuperSurv")
dat <- metabric[1:40, ]
x_cols <- grep("^x", names(dat))[1:3]
X <- dat[, x_cols, drop = FALSE]
newX <- X[1:10, , drop = FALSE]
times <- seq(50, 150, by = 50)

fit <- surv.coxph(
  time = dat$duration,
  event = dat$event,
  X = X,
  newdata = newX,
  new.times = times,
  obsWeights = rep(1, nrow(dat)),
  id = NULL
)

eval_cindex(
  time = dat$duration[1:10],
  event = dat$event[1:10],
  S_mat = fit$pred,
  times = times,
  eval_time = 100,
  method = "uno"
)
#> [1] 0.5898251