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TomHsiung
Quartz | Level 8

Hello, everyone

 

I am practicing COX regression. I see from the SAS support webpage that, after PROC PHREG, we can plot cumulative hazard graphs with the 95% confidence limits. However, I would like to plot the cumulative hazard graphs with the 95% confidence interval. I did not find the option from the webpage to do so.

 

As you know, 95%CL is much wider than 95%CI. I see some research publications have cumulative hazard graphs with 95%CI.

 

I would like to hear your ideas, thanks.

 

Partial code:

proc phreg data = DSP2_raw  plots(overlay = bygroup) = (survival cumhaz);
class v1(ref='0')
v2(ref='0')
v3(ref='0')
v4(ref='0')
v5(ref='0');
model TimeEvent*Event(0) = v1
v2
v3
v4
v5
v6
v7
...
vn / rl = wald;
baseline covariates = predict;
run;
1 ACCEPTED SOLUTION

Accepted Solutions
sbxkoenk
SAS Super FREQ

@TomHsiung wrote:

As you know, 95%CL is much wider than 95%CI.


????

Confidence limits are the numbers at the upper and lower end of a confidence interval.
Are you referring to prediction band?
A prediction interval is less certain (hence wider) than a confidence interval. That's because a prediction interval predicts an individual number, whereas a confidence interval is for the mean.

 

Koen

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6 REPLIES 6
sbxkoenk
SAS Super FREQ

@TomHsiung wrote:

As you know, 95%CL is much wider than 95%CI.


????

Confidence limits are the numbers at the upper and lower end of a confidence interval.
Are you referring to prediction band?
A prediction interval is less certain (hence wider) than a confidence interval. That's because a prediction interval predicts an individual number, whereas a confidence interval is for the mean.

 

Koen

TomHsiung
Quartz | Level 8

@sbxkoenk Hi, pal. Thank you for your reply.

Oh! I thought the CL option in plots(overlay cl) was the prediction interval. Probably, I was misled by chatGPT, I think. I remember chatGPT told me CL (confidence limits) and CI (confidence intervals) were different. At the same time, my data showed a very wide band, which led me to the wrong conclusion.

 

Thank you for your clarification. Appreciated!

TomHsiung
Quartz | Level 8

Update:

 

When plots option, overlay & cl, are used together, no CL bands. It shows CL bands when plots option has only cl.

proc phreg data = cox_raw plots(overlay cl) = cumhaz;

 

sbxkoenk
SAS Super FREQ

@TomHsiung wrote:

Update:

When plots option, overlay & cl, are used together, no CL bands. It shows CL bands when plots option has only cl.

proc phreg data = cox_raw plots(overlay cl) = cumhaz;

That's not my experience.

I have just submitted :

ods graphics on;
proc phreg data=Myeloma plots(overlay cl)=cumhaz;
   model Time*VStatus(0)=LogBUN HGB;
   baseline covariates=Inrisks out=Pred1 survival=_all_/rowid=Id;
run;

... and it properly shows everything asked for.

 

Koen

TomHsiung
Quartz | Level 8

@sbxkoenk Much appreciate for your additional information. I can see that you do researches about INR, haha.

 

Below is my codes. I don't know what is wrong. Another thing is that I switched from SAS 9.4 to SAS Viya (update: I have tested these code lines on SAS OnDemand, and no CL bands there on cumhaz graph).

 

proc phreg data = cox_raw plots(overlay cl) = cumhaz;
class genderC(ref = '0') AF(ref = '0') Hypertension(ref = '0') CHF(ref = '0') akiC(ref = '0')
ddiC(ref = '0') indicationC(ref = '0') CYP2C9code(ref = '0') VKORC1Code(ref = '0') Warfarin_History(ref = '0');
model timeToFirstInrAttain*firstInrAttain(0) = bsa ageY genderC AF Hypertension CHF 
serumalb akiC ddiC indicationC CYP2C9code VKORC1code Warfarin_History / rl=wald;
baseline covariates = predict_cox;
run;

 

sbxkoenk
SAS Super FREQ

Hello,

 

Also on Viya it's working for me (I am using Viya 4 Stable 2024.06).

 

What SAS Viya version are you using?

Submit:

%PUT &=sysvlong4;

... to find out. See LOG-screen for the answer.

 

I cannot spot an error in your code.
You can also contact SAS Technical Support (TS) for this. You can do so via the SAS Customer Service Portal (customer portal).
https://service.sas.com/csm

 

Koen

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