Seeking suggestions for Power analysis in Survival Analysis

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Seeking suggestions for Power analysis in Survival Analysis

William Dudley-2
Apologies in advance - this is off topic

I need to estimate sample size for a COX proportional hazard analysis with repeated measures.  The data will come from patients who are treated on multiple occasions (the repeated measure) and we will be looking at time to new  treatment (such as IV to oral for instance).  We anticipate that patients may have on average 5 treatment episodes.

I can estimate sample size with PASS but I don't know how to adjust for the repeated measures and wonder if there are alternative sample size estimation routines that I might employ.

Thanks in advance
Bill


--
William N. Dudley, PhD
Professor - Public Health Education
The School of Health and Human Sciences
The University of North Carolina at Greensboro
437-L Coleman Building
Greensboro, NC 27402-6170
See my research on
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Re: Seeking suggestions for Power analysis in Survival Analysis

Will M @ G

Might check into G-Power, it has various options that could fit

> On 12/31/2019 12:51:55 PM, William Dudley ([hidden email]) wrote:
> > Apologies in advance - this is off topic
>
> I need to estimate sample size for a COX proportional hazard analysis with
> repeated measures.  The data will come from patients who are treated on
> multiple occasions (the repeated measure) and we will be looking at time to
> new  treatment (such as IV to oral for instance).  We anticipate that
> patients may have on average 5 treatment episodes.
>
> I can estimate sample size with PASS but I don't know how to adjust for the
> repeated measures and wonder if there are alternative sample
> size estimation routines that I might employ.
>
> Thanks in advance
> Bill
>
>
> --
> William N. Dudley, PhD
> Professor - Public Health Education
> The School of Health and Human Sciences
> The University of North Carolina at Greensboro
> 437-L Coleman Building
> Greensboro, NC 27402-6170
> See my research on
> GoogleScholar <https://scholar.google.com/citations?user=ZiYmyb4AAAAJ

===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
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Re: Seeking suggestions for Power analysis in Survival Analysis

Bruce Weaver
Administrator
In reply to this post by William Dudley-2
Hi Bill.  I am curious about how you intend to carry out Cox regression with
repeated measures.  If you can show us that, someone might be able to
suggest a way to do your sample size estimate via simulation.  

Cheers,
Bruce



William Dudley-2 wrote

> Apologies in advance - this is off topic
>
> I need to estimate sample size for a COX proportional hazard analysis with
> repeated measures.  The data will come from patients who are treated on
> multiple occasions (the repeated measure) and we will be looking at time
> to
> new  treatment (such as IV to oral for instance).  We anticipate that
> patients may have on average 5 treatment episodes.
>
> I can estimate sample size with PASS but I don't know how to adjust for
> the
> repeated measures and wonder if there are alternative sample
> size estimation routines that I might employ.
>
> Thanks in advance
> Bill
>
>
> --
> William N. Dudley, PhD
> Professor - Public Health Education
> The School of Health and Human Sciences
> The University of North Carolina at Greensboro
> 437-L Coleman Building
> Greensboro, NC 27402-6170
> See my research on
> GoogleScholar
> &lt;https://scholar.google.com/citations?user=ZiYmyb4AAAAJ&amp;hl=en&gt;
> ResearchGate &lt;https://www.researchgate.net/profile/William_Dudley&gt;
> VOICE 336.256 2475
>
> [image: email signature image example.png]
>
> =====================
> To manage your subscription to SPSSX-L, send a message to

> LISTSERV@.UGA

>  (not to SPSSX-L), with no body text except the
> command. To leave the list, send the command
> SIGNOFF SPSSX-L
> For a list of commands to manage subscriptions, send the command
> INFO REFCARD





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Re: Seeking suggestions for Power analysis in Survival Analysis

Rich Ulrich
In reply to this post by William Dudley-2
Questions. 
You don't specify any hypothesis.  Is this a two-group
comparison?  "time to new treatment" is an outcome, but
that just gives you a score.

Is the "time" measured by looking at change-in-treatments
1-5 as measured from "1"?  - Is there a date-measure, or is
the score simply the difference, one to four, from subtraction
of 2-1, 3-1, 4-1 ,5-1? 

How often will there be multiple outcomes possible for one
patient?  Or, should this be a survivorship analysis?

If your hypothesis does come down to a 1 d.f. test, you can
keep in mind that other power analyses for rather similar
analysis models will give similar results.  Consider the other
information that you will eventually want to report.

If there are two groups, and mostly just one outcome, the
most simple version of an analysis would be the t-test between
groups, comparing time-to-outcome for the first outcome.  I'm
not saying that that should be your analysis, but the power
considerations are intrinsically similar.  Multiple outcomes give
improvement in power.

That is, the simple power analysis on the t-test gives you a /maximum/,
estimate of sample size needed for a certain amount of power, where
the extra "new-treatment" scores per-person should result in slightly
better power (fewer N required) for the more sophisticated analysis.

Or, if there are /many/ changes in treatment, perhaps you could
consider the t-tests between two groups, where you compare "the
number of treatment changes"  for a simplified power analysis. That's
another thing you will want to report.


--
Rich Ulrich

From: SPSSX(r) Discussion <[hidden email]> on behalf of William Dudley <[hidden email]>
Sent: Tuesday, December 31, 2019 12:51 PM
To: [hidden email] <[hidden email]>
Subject: Seeking suggestions for Power analysis in Survival Analysis
 
Apologies in advance - this is off topic

I need to estimate sample size for a COX proportional hazard analysis with repeated measures.  The data will come from patients who are treated on multiple occasions (the repeated measure) and we will be looking at time to new  treatment (such as IV to oral for instance).  We anticipate that patients may have on average 5 treatment episodes.

I can estimate sample size with PASS but I don't know how to adjust for the repeated measures and wonder if there are alternative sample size estimation routines that I might employ.

Thanks in advance
Bill


--
William N. Dudley, PhD
Professor - Public Health Education
The School of Health and Human Sciences
The University of North Carolina at Greensboro
437-L Coleman Building
Greensboro, NC 27402-6170
See my research on
ResearchGate
VOICE 336.256 2475

email signature image example.png

===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD