hazard.ratio.plot {Design} | R Documentation

## 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
f.harrell@vanderbilt.edu

### See Also

`cox.zph`, `residuals.cph`, `coxph.fit`, `cph`, `coxph`, `Surv`

### Examples

    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')

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