A SAS macro for direct adjusted survival curves based on Aalen's additive model

Aalen's additive model defines the covariate effects on the survival outcome to be time-varying. The aim of this paper is to explore the application of Aalen's model in assessing treatment effects, adjusting for possibly different patient profiles between the treatment groups. We treat Aalen's model as the underlying model and compute the direct adjusted survival curves for different treatments. The treatment comparison can be performed by finding a confidence interval for the difference between two direct adjusted survivals. We developed a SAS macro that calculates the direct adjusted survival estimates and the standard errors, based on Aalen's model. In this paper, we give two examples to explain the syntax for using the macro.