/******************************************************************
* 限制性平均生存时间（RMST）完整示例
* 数据: example.csv（原创模拟 ADTTE 风格数据）
* 方向: Drug A - Placebo；限制时间 tau=365 天
* 环境: SAS 9.4 / SAS/STAT 15.1+
******************************************************************/

proc import datafile="example.csv" out=adtte dbms=csv replace;
  guessingrows=max;
run;

data adtte_os;
  set adtte;
  where upcase(paramcd)='OS' and upcase(anl01fl)='Y';
run;

ods graphics on;
ods output RMST=rmst_estimates
           RMSTDiff=rmst_difference
           RMSTTest=rmst_global_test;
proc lifetest data=adtte_os rmst(tau=365) plots=rmst;
  time aval*cnsr(1);
  strata trt01p / diff=control('Placebo');
run;
ods output close;
ods graphics off;

data rmst_difference_ci;
  set rmst_difference;
  difference=estimate;
  lower_cl=difference-quantile('NORMAL',0.975)*stderr;
  upper_cl=difference+quantile('NORMAL',0.975)*stderr;
  label difference='RMST difference (Drug A - Placebo)'
        lower_cl='Normal-approximation 95% lower CL'
        upper_cl='Normal-approximation 95% upper CL';
run;

proc print data=rmst_difference_ci noobs label;
  var group1 group2 difference stderr lower_cl upper_cl probchisq;
run;

/* RMST_ESTIMATES: 每组到 Day 365 的曲线下面积与标准误
   RMST_DIFFERENCE_CI: Drug A - Placebo 的差、正态近似 95% CI 与 p 值 */