calculation of risk difference

[kalbo]

Hi all, I need to add the calculated Risk Difference to listings of preferred terms for a trial. There are 2 arms: dose and placebo.

Per FDA standards, I would like to add risk difference with 95% confidence intervals. This can be added to either the AE data set, or to the proc report.

prefterm             dose      placebo  riskdifference

Cold                       3            2

Flu                          2             1

Headache             1             3

[sbxkoenk]

You need to specify the RISKDIFF option in PROC FREQ.

The FREQ Procedure

Risks and Risk Differences
https://go.documentation.sas.com/doc/en/statug/15.2/statug_freq_details54.htm

Ciao, Koen

[kalbo]

Thanks for your reply. Do you know how data should be structured before using proc freq?

[sbxkoenk]

See documentation : 

SAS Help Center: Inputting Frequency Counts

PROC FREQ can use either raw data or cell count data to produce frequency and crosstabulation tables. Raw data, also known as case-record data, report the data as one record for each subject or sample member. Cell count data report the data as a table, listing all possible combinations of data values along with the frequency counts.

The statistics for contingency tables include the following:

• chi-square tests and measures

• measures of association

• risks (binomial proportions) and risk differences for 2 x 2 - tables 

• odds ratios and relative risks for 2 x 2 - tables

• tests for trend

• tests and measures of agreement

• Cochran-Mantel-Haenszel statistics

Ciao, Koen