How do I get the 95% Confidence Limits for multiple data points in proc lifetest?

[hpatel3]

 Hello,

I'm trying to get 95% confidence limits for 5, 10, and 15 year individually on my on my KM survival curve. I know how to get the bands on my plot using  plots=(survival(cb=hw)), but how do I get the specific confidence limit for each of my 3 data points? All I get with my current code are the quartile estimates.

I'm using Proc LifeTest and here is my code by the  way. What I don't know is if I'm supposed use an ODS statement, or if there is a step within proc-lifetest  to calculate the 95% CIs. and WHERE in my code is this step supposed to go? (fairly new to SAS)

My code is below:

libname Hetal "\\tuftsmc\home\hpatel3\SAS Datasets";
run; 

proc import out=hetal.ES_database datafile="\\tuftsmc\home\hpatel3\SAS Datasets\ES Database Edit.csv" dbms=csv replace;  getnames=yes; datarow=2; 
run;
ods graphics on / attrpriority=color; 
Ods output survivalplot=survplot;
proc lifetest data=hetal.es_database conftype=loglog plot=(s) plots=(survival(cb=hw))
timelist=(5 10) outs=survival_rates reduceout; 
time FU_Total*Status(0);
Title"5 & 10 Year Survival Estimate for ES";
run;

proc sgplot data=survplot noborder nowall;
step x=Time y=Survival / lineattrs=(color=darkblue thickness=2);
xaxis display=(noticks) label="Years" values=(0 to 10 by 2) min=0 max=10 labelattrs=(size=10 weight=bold );
yaxis label='Survival Probability' values=(0 to 1.0 by 0.2) min=0 max=1.0 labelattrs=(size=10 weight=bold);
inset / title="95% CI:10.4476 (5.770, 16.2245) " position=bottomright;
run;

[Reeza]

Did you check all your output data sets?

Particularly, survival_rates?

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@hpatel3 wrote:

 Hello,

I'm trying to get 95% confidence limits for 5, 10, and 15 year individually on my on my KM survival curve. I know how to get the bands on my plot using  plots=(survival(cb=hw)), but how do I get the specific confidence limit for each of my 3 data points? All I get with my current code are the quartile estimates.

I'm using Proc LifeTest and here is my code by the  way. What I don't know is if I'm supposed use an ODS statement, or if there is a step within proc-lifetest  to calculate the 95% CIs. and WHERE in my code is this step supposed to go? (fairly new to SAS)

My code is below:

libname Hetal "\\tuftsmc\home\hpatel3\SAS Datasets";
run; 

proc import out=hetal.ES_database datafile="\\tuftsmc\home\hpatel3\SAS Datasets\ES Database Edit.csv" dbms=csv replace;  getnames=yes; datarow=2; 
run;
ods graphics on / attrpriority=color; 
Ods output survivalplot=survplot;
proc lifetest data=hetal.es_database conftype=loglog plot=(s) plots=(survival(cb=hw))
timelist=(5 10) outs=survival_rates reduceout; 
time FU_Total*Status(0);
Title"5 & 10 Year Survival Estimate for ES";
run;

proc sgplot data=survplot noborder nowall;
step x=Time y=Survival / lineattrs=(color=darkblue thickness=2);
xaxis display=(noticks) label="Years" values=(0 to 10 by 2) min=0 max=10 labelattrs=(size=10 weight=bold );
yaxis label='Survival Probability' values=(0 to 1.0 by 0.2) min=0 max=1.0 labelattrs=(size=10 weight=bold);
inset / title="95% CI:10.4476 (5.770, 16.2245) " position=bottomright;
run;

---

[hpatel3]

yes! I have the survival rates and quartile estimates, but not the confidence limits.

[Reeza]

Hmm...please post a proc contents on the survival_rates data set. 

Note that your next step uses the survplot data set not the survival_rates data. 

proc contents data=survival_rates;run;

From the documentation the OUTSURV/OUTS data sets include the following, which is what I get in my test. What happens if you run the code below? Does that generate the confidence intervals?

title 'Survival of Males with Angina Pectoris';
data Males;
   keep Freq Years Censored;
   retain Years -.5;
   input fail withdraw @@;
   Years + 1;
   Censored=0;
   Freq=fail;
   output;
   Censored=1;
   Freq=withdraw;
   output;
   datalines;
456   0 226  39 152  22 171  23 135 24 125 107
 83 133  74 102  51  68  42  64  43 45  34  53
 18  33   9  27   6  23   0  30
;

ods graphics on;
proc lifetest data=Males 
              plots=(s,ls,lls,h,p) outs=survival_Rates timelist = (0 to 15 by 3) reduceout;
   time Years*Censored(1) ;
   freq Freq;
   
run;
ods graphics off;

OUTSURV= Data Set

You can specify the OUTSURV= option in the PROC LIFETEST statement to create an output data set that contains the survival estimates. The data set contains the following columns:

• any specified BY variables

• a numeric variable STRATUM that numbers the strata, if you specify the STRATA statement

• any specified STRATA variables, their values coming from either their original values or the midpoints of the stratum intervals if endpoints are used to define strata (semi-infinite intervals are labeled by their finite endpoint)

• the GROUP= variables, if you specify the GROUP= option in the STRATA statement

• the time variable as specified in the TIME statement. For METHOD=KM, METHOD=BRESLOW, or METHOD=FH, it contains the observed failure or censored times. For the life-table estimates, it contains the lower endpoints of the time intervals.

• SURVIVAL, a variable that contains the survivor function estimates

• CONFTYPE, a variable that contains the name of the transformation applied to the survival time in the computation of confidence intervals

• SDF_LCL, a variable that contains the lower limits of the pointwise confidence intervals for the survivor function

• SDF_UCL, a variable that contains the upper limits of the pointwise confidence intervals for the survivor function

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@hpatel3 wrote:

yes! I have the survival rates and quartile estimates, but not the confidence limits.

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