hazard.ratio.plot: Hazard Ratio Plot

In rms: Regression Modeling Strategies

Hazard Ratio Plot

Description

The hazard.ratio.plot function repeatedly estimates Cox regression coefficients and confidence limits within time intervals. The log hazard ratios are plotted against the mean failure/censoring time within the interval. Unless times is specified, the number of time intervals will be \max(round(d/e),2), where d is the total number of events in the sample. Efron's likelihood is used for estimating Cox regression coefficients (using coxph.fit). In the case of tied failure times, some intervals may have a point in common.

Usage

hazard.ratio.plot(x, Srv, which, times=, e=30, subset,
                  conf.int=.95, legendloc=NULL, smooth=TRUE, pr=FALSE, pl=TRUE,
                  add=FALSE, ylim, cex=.5, xlab="t", ylab, antilog=FALSE, ...)

Arguments

x	a vector or matrix of predictors
Srv	a Surv object
which	a vector of column numbers of x for which to estimate hazard ratios across time and make plots. The default is to do so for all predictors. Whenever one predictor is displayed, all other predictors in the x matrix are adjusted for (with a separate adjustment form for each time interval).
times	optional vector of time interval endpoints. Example: times=c(1,2,3) uses intervals [0,1), [1,2), [2,3), [3+). If times is omitted, uses intervals containing e events
e	number of events per time interval if times not given
subset	vector used for subsetting the entire analysis, e.g. subset=sex=="female"
conf.int	confidence interval coverage
legendloc	location for legend. Omit to use mouse, "none" for none, "ll" for lower left of graph, or actual x and y coordinates (e.g. c(2,3))
smooth	also plot the super–smoothed version of the log hazard ratios
pr	defaults to FALSE to suppress printing of individual Cox fits
pl	defaults to TRUE to plot results
add	add this plot to an already existing plot
ylim	vector of y-axis limits. Default is computed to include confidence bands.
cex	character size for legend information, default is 0.5
xlab	label for x-axis, default is "t"
ylab	label for y-axis, default is "Log Hazard Ratio" or "Hazard Ratio", depending on antilog.
antilog	default is FALSE. Set to TRUE to plot anti-log, i.e., hazard ratio.
...	optional graphical parameters

Author(s)

Frank Harrell
Department of Biostatistics, Vanderbilt University
[e-mail]

See Also

cox.zph, residuals.cph, survival-internal, cph, coxph, Surv

Examples

require(survival)
n <- 500
set.seed(1)
age <- 50 + 12*rnorm(n)
cens <- 15*runif(n)
h <- .02*exp(.04*(age-50))
d.time <- -log(runif(n))/h
label(d.time) <- 'Follow-up Time'
e <- ifelse(d.time <= cens,1,0)
d.time <- pmin(d.time, cens)
units(d.time) <- "Year"
hazard.ratio.plot(age, Surv(d.time,e), e=20, legendloc='ll')

rms documentation built on Sept. 11, 2024, 7:51 p.m.