Dear statalist,
I have a dataset with multiple records per person with time varying covariates. I am running
survival analysis with the tvc option in stcox and have found 2 variables with significant time
interactions. My questions are:
(1) Am I setting up the stcox statement correctly (see code below)
(2) Regarding the interpretation- Is it correct to say that the variable var1 has a hazard of 0.35
with the relative hazard then decreasing by a factor of 1.00 with each unit of _t?
Any comments or suggestions would be appreciated!
Best regards,
Jennifer Evans
. xi: stcox yrsinj_b age_b gender_b var1 var2 var3 var4, nolog noshow tvc(var1 var3)
Cox regression -- Breslow method for ties
No. of subjects = 360 Number of obs = 1577
No. of failures = 104
Time at risk = 226907
LR chi2(16) = 117.25
Log likelihood = -467.29121 Prob > chi2 = 0.0000
------------------------------------------------------------------------------
_t | Haz. Ratio Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
rh |
yrsinj_b | 1.033031 .029971 1.12 0.263 .9759283 1.093476
age_b | .9916956 .0319112 -0.26 0.796 .9310822 1.056255
gender_b | 1.114194 .2912036 0.41 0.679 .6675631 1.859641
var1 | .3489511 .1266303 -2.90 0.004 .1713457 .7106501
var2 | .3903011 .1237031 -2.97 0.003 .2097093 .7264101
var3 | .2174367 .0915801 -3.62 0.000 .0952409 .496412
var4 | 1.562432 .3349837 2.08 0.037 1.026371 2.378471
-------------+----------------------------------------------------------------
t |
var1 | 1.001592 .000593 2.69 0.007 1.00043 1.002755
var3 | 1.001354 .0005982 2.26 0.024 1.000182 1.002527
------------------------------------------------------------------------------
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