help for stkap

Adjusted Kaplan-Meier Curves

stkap [if exp] [in range],
[by(varlist)
strata(varlist)
adjust(covlist)
graph_options]

Description

stkap graphs the Kaplan-Meier survivor function by categories of one or
more nominal X variables adjusted for covariates. The only difference
between this and sts graph is the covariates are centered by default
based on the observations used in the analysis, or can be set to specified
values. If the adjust option is not specified, stkap reduces
to unadjusted KM plots; You must have stset your data before using
this command.

Options

by(varlist) graphs separate curve for each category of
varlist; produces separate survivor functions by making separate
calculations for each group identified by equal values of the by()
variables.

strata(varlist) graphs separate curve for each category of
varlist; stratified estimates (equal coefficients across strata but
baseline hazard unique to each stratum) are then estimated. May be used
with adjust() in place of by()

adjust(covlist) lists any covariates. If none are specified,
unadjusted estimates are reported. Covariates are set to their mean, based
on observations used in the analysis, or can be set to user specified
values (e.g., age=50 gender=1).

Examples

. stset weeks, failure(relapse)
. stkap, strata(trtment) adj(wbcc)

Plots the Kaplan-Meier curves for weeks to relapse for leukemia
patients by categories of treatment, adjusted for white blood cell count

. stset days, failure(died)
. stkap, by(celltype) adj(trt=1 severity)

Plots the Kaplan-Meier curves for days until death for lung cancer
patients by cancer cell type, adjusted for treatment=1 and mean severity

Also see

Manual: [R] sts graph

Online: help for st, stset, sts graph

Author

J.M.Garrett, Professor, Department of Medicine, University of North Carolina,
Chapel Hill, NC.
Email: joanne_garrett@med.unc.edu