I work with registry data from national registries and often, when doing survival analysis, I have to account for left-truncation. I am a big fan of using the 'assess ph' statement to evaluate proportionality and linearity of covariates, since it is superior to manual, individual testing of each covariate and has been proven/evidenced to be reliable. Unfortunately, when using Proc Phreg in tandem with delayed entry, using either syntax :
The 'assess ph' statement is not included/functional. The zph statement is a poor substitute, as the supremum test P-values are not valid (no scientific backing) and relies on graphical interpretation.
This forces me to use R and the packages (prodlim) and (mets) instead. However, I would really like to stay within the SAS working environment, not having to skip back and forth between the two.