Hello guros,
I’m doing follow-up analysis of operated abdominal aneurysms. Time to death is the main outcome. Each patient is given a variable (what proportion of EVAR technique is used at the hospital) and the main question is if more use of EVAR affect mortality. There are 29 hospitals and there are alsom some 9 potential confounders and 8 other variables that might help in imputation. There are 4868 patients.
First I use survSplit to establish a counting process notation and divide patient observation in up to three lines (timeperiod 0 -1/2year, >1/2 -3 years, > 3 years - max 10 years).
Then imputation is done with aregImpute
Finally fit mult.impute with coxph is used nested in strata(timeperiod).
All this gives a reasonable result.
Now I want to do cox.zph on the result from fit mult.impute to evaluate the ‘prortional hazards assumption’ within each timeperiod
Unfortunately I get
Error in order(istrat, y[, 1]) : argument lengths differ.
A few years ago I managed to do this with success and reasonable results
in a simular analysis
Unfortunatle a cup of tea in the keyboard of that computers killed it so I can not study how I made the analysis.
Has the used program changed or is it impossible to test for ‘proportiomal hazards’ in this situation?
Any help highly appreciated
Yours sincerely Fredrik L