Programming the statistical procedures from SAS

Estimate Median Survival Time

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Regular Contributor
Posts: 220

Estimate Median Survival Time

I have been given a hazard ratio = 0.64 and a control median of 8 months.  How can I use that information to estimate the treatment median survival time at 80% power and show 38% improvement in hazard ratios?

Respected Advisor
Posts: 2,655

Estimate Median Survival Time

Check out PROC POWER, and look at the syntax for TWOSAMPLESURVIVAL.  I am pretty sure that you just need to plug in the values, and exponentiate the hazard rate for the reference group.  There is an example 70.6 in the SAS/STAT 9.3 documentation to get started.

Steve Denham

Trusted Advisor
Posts: 2,114

Estimate Median Survival Time

I don't think that you can do both of those from the little information you have provided.  See

http://www.statsdirect.com/help/sample_size/sample_size_for_survival_analysis.htm

for an easy to use survival analysis sample size computation.

Given the ratio and one rate, you can compute the sample size required for 80% power.

You can compute a 38% "improvement in hazard ratios" (though it is not to me well defined) to get a new HR, and then do the computation above.

I believe the SAS Power and Sample Size product can do the can computations.

Doc Muhlbaier

Duke

Regular Contributor
Posts: 220

Estimate Median Survival Time

I guess I should have specified that we already have a sample size of 200.  I hope that clears up a little bit.

Respected Advisor
Posts: 2,655

Estimate Median Survival Time

I guess I don't understand the question.  If you have a known sample size and known power, do you wish to solve for the minimum detectable difference?  You have specified what the difference is, so that seems out.  More info would help here.

Thanks,

Steve Denham

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