Interaction term in cox proportional hazard

sulafa — Mon, 20 Jun 2022 17:46:07 GMT

Hello SAS users,

I made cox proportional code, it runs without errors in the log, but I have some missing values(HR, CI) I need to test for interaction of my primary exposure iron(ironcat) with vitamin c(vitccat). also, how I can get a survival analysis graph with the same code? Thanks in advance

here is my code:

proc phreg data = CANIMPT.capstoneclean covs(aggregate) covm;
class ironcat vitccat;
model fup_t1d*case_t1d(0) = ironcat ironcat *vitccat /ties=discrete risklimits covb;
hazardratio "iron unadjusted" ironcat / diff=ref cl=wald;
title 'Ironcat consumption and T1D progression';
run;

Re: Interaction term in cox proportional hazard

OsoGris — Tue, 21 Jun 2022 08:06:23 GMT

You don't get HR for interaction terms in the ParameterEstimates table. You need to use a HAZARDRATIO statement with the AT= option to specify the level of the interacting variable. Also, the COVS(AGGREGATE) does nothing unless you have an ID statement to identify the clusters.

proc phreg data = CANIMPT.capstoneclean covs(aggregate) covm;
class ironcat vitccat;
model fup_t1d*case_t1d(0) = ironcat ironcat *vitccat /ties=discrete risklimits covb;
hazardratio "iron unadjusted" ironcat / diff=ref cl=wald;
title 'Ironcat consumption and T1D progression';
run;
You will also need the PLOTS= option on the PROC PHREG statement in conjunction with the BASELINE statement in the code. See Example 8 Survival Curves in the PHREG documentation for the basics.

topic Interaction term in cox proportional hazard in Statistical Procedures

Interaction term in cox proportional hazard

Re: Interaction term in cox proportional hazard