st: weird results...

classic Classic list List threaded Threaded
1 message Options
Reply | Threaded
Open this post in threaded view
|

st: weird results...

Christopher Intemann-3
Hello,
I'm trying to calculate the IRR for multiple events in a longitudinal  
study dataset.
I therefore stset the data:

stset Event_date if disease_no==0 & cond==1, id(ID)  
failure(disease_yes==1) origin(time birthdate) enter(time birthdate)  
exit(Visit==50)
replace _t0=_t0+t_ex

Then I'm splitting the dataset to exclude non important time periods:

stsplit x_split, at(60 761) trim

Now, when I calculate the rate, I receive something like:

strate gene if x_split==60,per(365.25)

GT Rate
CC 0.64
CT 0.53
TT 0.55

-> the rate of disesase-attacs is lower for the CT/TT-genotype, right?

Now, when I calculate the inicidence rate ratio (IRR) on the same st-
set data, I get:

xi: poisson _events i.gene if risktime>0&x_split==60,  
exposure(risktime) irr

GT IRR(CI) P
CC 1
CT 1.11 (1.03 - 1.19) 0.005
TT 1.14 (1.04 - 1.24) 0.005

According to these results, the IRR is HIGHER for the CT/TT-genotype.
This is weird. I guess there is something wrong.
Any help would be appreciated!
Thanks,
  Chris

smime.p7s (3K) Download Attachment