proc seqdesign: can you specify two alts (lower and upper)?

El-Aura — Mon, 26 Apr 2021 20:59:21 GMT

Hi there!

I'm trying to replicate a two-sample survival design using proc seqdesign. It has 2 stages (one interim at 73% of the information, one final at 100% information). One-sided alpha=0.025 power=0.835 (beta=0.165). O'Brien Fleming boundary will be implemented for efficacy and the Haybittle-Peto boundary will be implemented for futility. Assumed hazard ratio=0.58. Median survival time in the control arm is 42 months. Here're my codes:

ods graphics on;
proc seqdesign stopprob errspend boundaryscale=pvalue;
OneSidedOBFandHP: design alt=lower alpha=0.025 beta=0.165 nstages=2
method(reject)=obf method(accept)=hp(Z=0.489)
stop=both(betaboundary=nonbinding) info=cum(0.73 1);
model=twosamplesurvival (hazardratio=0.58 nullmedsurvtime=42);
ods output Boundary=Bnd_Time;
run;
ods graphics off;

But the results (stopping p-value boundaries) are not the same as the design I'm trying to replicate which has boundaries like:

A friend said that the problem is with "alt=lower" since for futility, alt should be "upper". But you can't specify two alts in seqdesign right? So is this the problem? How should I modify my codes to get the design I want to replicate (the screenshot above)?

Many thanks!!!

topic proc seqdesign: can you specify two alts (lower and upper)? in Statistical Procedures

proc seqdesign: can you specify two alts (lower and upper)?