***********************************************************************
* This is a program that illustrates the use of PROC PHREG in SAS     *
* to perform proportional hazards regression.                         *
*                                                                     *
* The sample data set is based on the results from an SE trial on 83  *
* patients with malignant mesothelioma, an uncommon lung cancer that  *
* is strongly associated with asbestos exposure.  Patients underwent  *
* one of three types of surgery, namely, biopsy, limited resection,   *
* and extrapleural pneumonectomy (EPP).  Treatment assignment was     *
* based on the extent of disease at the time of diagnosis.            *
***********************************************************************;

proc format;
value sexfmt 0='female' 1='male';
value psfmt 0='low' 1='high';
value wtchgfmt 1='no' 2='yes';
value surgfmt 1='biopsy' 2='limited resection' 3='EPP';
value eventfmt 0='no' 1='yes';
run;

data mesoth;
input age sex ps hist wtchg surg pftime prog stime dead;
label age='Age'
      sex='Sex'
      ps='Performance Status'
      hist='Histologic Subtype'
      wtchg='Weight Change at DX'
      surg='Surgery Type'
      pftime='PFT Event'
      prog='PFtime Censoring'
      stime='Survival Time'
      dead='Death Event';
format sex sexfmt.
       ps psfmt.
       wtchg wtchgfmt.
       surg surgfmt.
       prog eventfmt.
       dead eventfmt.;
cards;
60 1 1 136 1 3 394   1 823  1
59 1 0 136 2 3 1338  0 1338 0
51 0 0 130 1 1 184   1 270  1
73 1 1 136 1 3 320   0 320  1
74 1 0 136 2 1 168   0 168  1
39 0 0 136 1 1 36    1 247  1
46 1 1 131 1 3 552   1 694  0
71 1 0 136 1 1 133   1 316  1
69 1 0 136 1 1 175   1 725  0
49 1 0 131 1 1 327   0 327  1
69 1 0 131 1 2 0     0 0    1
72 1 0 131 1 1 676   1 963  0
44 0 0 130 2 2 223   1 265  1
45 1 0 136 2 2 184   1 237  1
57 1 0 132 1 2 145   1 176  1
60 0 1 131 1 1 316   0 316  1
22 1 1 131 1 2 87    1 310  1
46 0 1 131 1 1 135   1 166  1
60 1 0 131 1 3 1     1 28   1
72 1 0 131 1 2 199   1 730  1
65 1 0 131 1 3 39    0 39   1
65 1 1 131 1 2 61    1 116  1
60 1 0 131 1 3 17    0 17   1
64 1 0 131 2 3 799   1 1229 1
61 1 0 131 2 1 61    1 294  1
38 1 0 131 1 1 176   1 322  1
65 1 1 136 1 3 6     0 6    1
73 0 1 131 1 2 292   1 422  1
74 1 0 136 2 2 22    1 22   1
76 1 0 136 1 1 106   1 375  1
57 1 1 131 1 3 248   1 302  1
60 0 0 .   1 1 63    1 365  1
56 1 0 136 1 1 145   1 387  1
62 0 0 136 1 1 104   1 327  1
60 1 0 131 1 1 20    1 247  1
67 0 0 131 1 1 181   1 669  1
64 1 0 131 1 2 89    1 948  1
67 1 1 136 1 1 0     1 400  1
56 0 1 131 1 2 724   1 1074 0
52 1 0 160 2 1 62    1 137  1
56 1 0 131 1 3 93    1 210  1
44 1 0 136 1 3 402   1 648  1
50 0 0 136 2 2 141   1 520  1
63 1 0 .   2 1 156   1 304  1
68 1 1 131 1 2 265   1 349  1
50 1 0 .   2 3 305   1 317  1
41 0 1 131 1 1 181   1 395  1
60 1 0 131 1 1 274   1 503  1
65 1 0 136 2 2 20    1 20   1
47 1 1 131 1 3 411   1 679  0
46 1 1 131 1 2 624   0 624  0
70 1 1 131 1 2 278   1 617  0
58 1 0 136 1 1 20    1 85   1
57 1 1 132 1 3 112   1 139  1
75 1 0 132 2 2 47    1 47   1
66 1 1 136 1 3 294   1 523  1
77 1 0  .  1 1 126   1 157  1
65 0 0  .  2 1 117   1 545  0
46 0 0 131 1 1 63    1 218  1
71 0 1 132 2 1 139   0 139  1
61 1 0 136 1 1 538   1 1170 0
58 1 0 131 1 3 390   1 722  1
49 1 1 136 1 3 1102  0 1102 0
50 1 0 136 1 3 166   1 182  1
73 1 0 136 1 2 58    1 136  1
44 1 0 136 1 1 406   0 406  1
47 0 1 131 1 3 1123  0 1123 0
68 1 0 136 1 1 1009  1 1029 0
66 1 0 132 1 2 37    1 112  1
46 1 1 131 1 1 104   1 764  1
56 1 1 136 1 2 33    1 225  1
68 1 1 136 1 1 20    1 122  1
59 1 0 136 1 2 73    1 165  1
58 0 0 131 1 1 4     0 4    1
66 1 1 132 2 2 205   1 361  1
82 1 0 160 1 1 78    0 78   1
73 1 0 131 1 1 1265  0 1265 1
57 0 0 130 1 2 273   1 318  1
72 1 1 136 2 1 2     1 362  1
69 1 1   . 1 2 1093  0 1093 0
64 0 1 130 1 1 475   0 475  1
65 1 1 130 1 2 292   0 292  1
72 1 1 130 1 2 324   1 499  0
run;

proc print data=mesoth;
title 'Mesothelioma Example';
run;

data mesoth2;
set mesoth;
biop_EPP=0;
lr_EPP=0;
if surg=1 then biop_EPP=1;
if surg=2 then lr_EPP=1;
wtchg=wtchg-1;
run;

proc phreg data=mesoth2;
model stime*dead(0)=biop_EPP lr_EPP age sex ps hist wtchg/selection=stepwise
      include=2 slentry=0.10 slstay=0.10 risklimits;
title2 "Proportional Hazards Regression of Survival Time";
run;