adjsurvlt

A SAS macro for estimating direct adjusted survival functions for time-to-event data with or without left truncation

Author

Zhen-Huan Hu novelkeny@gmail.com

Copyright

(C) 2019-2021 Zhen-Huan Hu

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

SAS and all other SAS Institute Inc. product or service names are registered trademarks or trademarks of SAS Institute Inc. in the USA and other countries.

Specifications

Function

%adjsurvlt

Parameters

Syntax	Description
indata	Specifies the input data set, which requires the following variables: a continuous variable for the observed time, an event indicator, a categorical variable indicating treatment groups, and covariates for the multi-variate model. For left-truncated data, the input data set also should contain the time to left truncation. Observations with missing values need to be excluded beforehand.
time	Specifies the observed time from the start of follow-up to the event of interest or right censoring, whichever happens first.
event	Specifies the event indicator variable. It takes 1 as event of interest and 0 as right censoring.
strata	Specifies the treatment group variable.
covlst	Specifies the covariate list. Multiple covariates can be separated by spaces. A | sign can be used to separate continuous/ordinal variables from discrete categorical variables. For example, if variable A is categorical and variable B is continuous/ordinal, covlst = A | B needs to be specified; if both are categorical, covlst = A B needs to be specified; and if both are continuous/ordinal, covlst = | A B needs to be specified.
ltime	Specifies the left truncation time. The macro assumes no left truncation if it is left unspecified.
seed	Specifies the seed for random number generation. By default, seed = 0 which makes the seed obtained from the Intel RdRand instruction if feasible, or the current time value.
nsim	Specifies the number of simulation processes for constructing confidence bands. By default, nsim = 1000.
mintime	Specifies the lower boundary of the time interval between which the confidence bands are constructed. By default, the macro takes the minimum observed event time for each treatment group. For confidence bands of the survival difference estimates, the macro uses the greater of the minimum observed event times between the treatment group pairs. If the specified value is less than the minimum observed event time, the macro falls back to the default.
maxtime	Specifies the upper boundary of the time interval between which the confidence bands are constructed. By default, the macro takes the maximum observed event time for each treatment group. For confidence bands of the survival difference estimates, the macro uses the greater of the maximum observed event times between the treatment group pairs. If the specified value exceeds the maximum observed event time, the macro falls back to the default.
alpha	Specifies the confidence level. By default, alpha = 0.05.
timelist	Specifies the time points at which to display the estimates. Setting it only affects the displayed results.
outdata	Specifies the name of the main output data set containing direct adjusted survival estimates. It also defines the prefixes of the names of three additional output data sets that contain summary information of the sample, survival difference estimates and simultaneous p values. The default value is outdata = adjout, which creates the following data sets: adjout which contains information associated with the adjusted survival estimates for individual treatment groups including event time, treatment groups, numbers at risk, survival estimates, standard error estimates, confidence limits and confidence bands; adjoutinfo which contains summary of the numbers of events and censored subjects as well as boundaries of the confidence bands; adjoutdiff which contains information associated with the survival difference estimates between treatment group pairs including event time, treatment group pairs, survival difference estimates, standard error estimates, confidence limits and confidence bands; adjouttest which contains information regarding the hypothesis testing of the difference between treatment group pairs including number of simulation processes, critical values, and simultaneous p values. The confidence limits and confidence bands for the adjusted survival estimates are calculated based on log-log transformation, while those for the survival difference estimates are based on linear transformation.
outsurvplot	Enables the macro to plot direct adjusted survival curves. When outsurvplot = 1 is set, the macro outputs a plot file named adjout-plot that displays a grid of adjusted survival curves, and when outsurvplot = 2 is set, a single plot with overlapped adjusted survival curves is produced instead.
outdiffplot	Enables the macro to plot direct adjusted survival difference curves. When outdiffplot = 1 is specified, an image file named adjoutdiff-plot is created that displays a grid of survival difference curves.
showci	Toggles whether to display confidence limits in plots. The macro displays confidence limits by default. Setting showci = 0 hides the confidence limits.
showcb	Toggles whether to display confidence bands in plots. The macro displays confidence bands by default. Setting showcb = 0 hides the confidence bands.
tickvalues	Specifies values of the tick marks on the x axis.
width	Specifies width of the plots. By default, width = 800px.
height	Specifies height of the plots. By default, height = 600px.
style	Specifies style of the plots. By default, style = statistical.
imagefmt	Specifies image format of the plots. By default, imagefmt = png.
noprint	Hides output results.

Reference

Hu, ZH., Wang, HL., Gale, R.P. et al. A SAS macro for estimating direct adjusted survival functions for time-to-event data with or without left truncation. Bone Marrow Transplant (2021). https://doi.org/10.1038/s41409-021-01435-2