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Re: st: pairwise comparison of a Survival data


From   "T. Alp Ozkan" <alpozkan@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: pairwise comparison of a Survival data
Date   Wed, 18 Apr 2012 08:30:11 +0300

Dear Listers,

Dealing with a this data set on survival analyses taught me a lot
however I stucked on this particular problem. Any opinion would be
great for me.

Thanks Alp



On Tue, Apr 17, 2012 at 1:43 PM, T. Alp Ozkan <alpozkan@gmail.com> wrote:
> Dear listers,
>
> I'm working on a data of renal carcinoma. In 2010 TNM cancer staging
> classification has been changed. According to this I want to validate
> new TNM classification. In a part of this analyse I need a pairwise
> survival comparisons of consecutive T stages (like T1avsT1b or T1b vs
> T2a)
>
> First I used  stcox for TNM 2010 and test each other.
>
> . stcox i.pT2010
>
>         failure _d:  CSS
>   analysis time _t:  followuptimemonths
>
> No. of subjects =         1889                     Number of obs   =      1889
> No. of failures =          151
> Time at risk    =  63708.43333
>                                                   LR chi2(6)      =    144.47
> Log likelihood  =   -949.97419                     Prob > chi2     =    0.0000
>
> ------------------------------------------------------------------------------
>          _t | Haz. Ratio   Std. Err.      z    P>|z|     [95% Conf. Interval]
> -------------+----------------------------------------------------------------
>  pT2010 |
>         11  |   2.879476   1.326301     2.30   0.022      1.16747     7.10201
>         21  |   5.796228   2.753477     3.70   0.000     2.284469    14.70638
>         22  |   10.66265   5.002194     5.04   0.000     4.251472    26.74184
>         30  |   14.05566   6.091828     6.10   0.000     6.010826    32.86763
>         31  |   48.52258   24.10974     7.81   0.000     18.32321     128.495
>         40  |   21.73121   9.848165     6.79   0.000     8.939966    52.82409
> ------------------------------------------------------------------------------
>
> . test 11.pT2010 21.pT2010
>
>  ( 1)  11.pT2010 = 0
>  ( 2)  21.pT2010 = 0
>
>           chi2(  2) =   14.33
>         Prob > chi2 =    0.0008
>
>
> As I read more help documents I realized another stratification with
> sts test variable, strata(subvariable) command.
>
> Would you help me to understand which one is suitable for this purpose?
>
> Thanks Alp
>
>
> . sts test pT2010, strata (T1bvsT2a)
>
>         failure _d:  CSS
>   analysis time _t:  followuptimemonths
>
>
> Stratified log-rank test for equality of survivor functions
>
>       |   Events         Events
> pT2010 |  observed    expected(*)
> -------+-------------------------
> T1b    |        22          28.29
> T2a    |        17          10.71
> -------+-------------------------
> Total  |        39          39.00
>
> (*) sum over calculations within T1bvsT2a
>
>             chi2(1) =       5.16
>             Pr>chi2 =     0.0231
>
> *
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> *   http://www.ats.ucla.edu/stat/stata/

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