rms (version 5.1-3.1)

# hazard.ratio.plot: 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

## See Also

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

## Examples

```# NOT RUN {
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')
# }
```