PROC PHREG with IPTW weighted cohort: robust standard error

[dac_js]

I have the following data:

data have;
input ID $ Time_to_Event Event Age Treatment $ Weight;
datalines;
01 12 1 45 A 1.2
02 34 0 50 B 1.0
03 25 1 60 A 1.5
04 44 0 55 B 0.8
05 15 1 65 A 1.1
06 8 0 40 B 0.9
07 20 1 70 A 1.4
08 30 0 35 B 1.3
09 22 1 42 A 1.0
10 18 0 57 B 1.2
11 36 1 48 A 1.1
12 40 0 53 B 0.7
13 5 1 62 A 1.6
14 28 0 37 B 1.5
15 16 1 44 A 0.8
16 45 0 56 B 1.0
17 9 1 39 A 1.3
18 27 0 51 B 1.2
19 33 1 64 A 0.9
20 11 0 46 B 1.4
;
run;

proc phreg data=have;
class Treatment;
model Time_to_Event*Event(0) = Age Treatment;
weight Weight;
run;

Is there a way to add robust standard error here to account for the weight added in the Cox regression?

[OsoGris]

Robust standard errors are produced by the COVSANDWICH(AGGREGATE) option on the PROC PHREG statement. You will also need an ID statement to list the variable that defines your clusters.