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lcmichael_unc
Fluorite | Level 6

Hi Folks,

I want to compute the overall stratum-adjusted difference in proportions (SVR12*TRTWKS) and confidence limits for the variable SVR12 in the following tables statement in a frequency procedure. I need the overall difference (and C.I.) in SVR12, controlling for CIRRHOSIS (Y/N) and HCVGTCAT (A/B) simultaneously but the following code is producing individual differences controlling independently for each pair of strata (e.g., CIRRHOSIS='Y', HCVGTCAT='A') and not controlling for all levels of both covariates simulateously. Many thanks for all insights.

 

proc freq data=&library..SVR_GP_mITT nlevels order=data;
tables CIRRHOSIS*HCVGTCAT*TRTWKS*SVR12 / riskdiff (column=both CL=(WALD WILSON)) chisq fisher cmh cl agree alpha=0.05;
format SVR12 svrfmt.;
where FIRSTREC=1;
ods output CrossTabFreqs=crstabfrq RiskDiffCol1=rskdfcol1 PearsonChiSq=pearchisq PdiffCLs=PdiffCLs ;
run;

2 REPLIES 2
lcmichael_unc
Fluorite | Level 6

All responders:

 

I think I found my answer: it requires the specification of the 'common' sub-option in the riskdiff option per:

 

tables CIRRHOSIS*HCVGTCAT*TRTWKS*SVR12 / tables HCVGTCAT*TRTWKS*SVR12 / 
riskdiff (common column=both CL=(WALD WILSON)) chisq fisher cmh cl agree alpha=0.05;

 

Please confirm. Thanks.

Watts
SAS Employee

Yes, the RISKDIFF(COMMON) option provides confidence limits for the overall stratum-adjusted risk (proportion) difference. Also, the COMMONRISKDIFF option provides additional confidence limit types, tests, and stratum weights. 

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