> Lost to Follow-up through 2 Years : 10%
I think you mean that 10% is the rate at which patients would drop out before the end of the study ASSUMING that they don't die from the hazard. If so, then the correct statement is
CensorRate = -log(0.9)/2;
because 90% SURVIVE the "dropout hazard".
The nice thing about simulation is you can test the code to see if it makes sense:
data Sim;
call streaminit(1234);
HazardRate = -log(0.6)/2;
CensorRate = -log(0.9)/2;
EndTime = 2; /* end of study period */
do PatientID = 1 to 500;
tEvent = rand('Expo', 1/HazardRate); /* eg, die */
c = rand('Expo', 1/CensorRate); /* eg, drop out */
t = min(tEvent, c, EndTime); /* time of die, drop out, or study ends */
Dropout = (c < EndTime); /* this person didn't drop out */
Survived = (tEvent > EndTime); /* this person didn't die */
Censored = (c < tEvent | tEvent > EndTime); /* this person dropped out or didn't die */
output;
end;
run;
proc means data=Sim N mean CLM;
var Dropout Survived;
run;
proc lifetest data=Sim plots=(survival(atrisk CL));
time t*Censored(1);
ods exclude ProductLimitEstimates;
ods output ProductLimitEstimates=S1;
run;
... View more
