Creating a graph showing incidence rate

[lisahoward]

I am trying to create graph plotting incidence rate of headache at -30 day intervals prior to baseline date

I am unsure how to calculate the negative person time for each time point to create the rate.

My graph will have the following x and y axis -365-0 for the time points and rates per 1000.

rate per 1000
1
0.5
0
-365	-330	-300	-270
timepoint

I have the following variables in my SAS dataset, Patient ID, baseline date (which will be represented be the 0 time point on my graph), headache (0/1), and headache date.  A patient can only have one headache max which is the earliest within the prior baseline 365 days.  Any help in calculating  the rate for each negative timepoint and then plotting it as a graph would be great.

Many thanks,

Lisa.

[djrisks]

Hi Lisa,

It's difficult for me to visualise your graph. Can you show an example of it please? Also please let us know the SAS Version you have and include an example of the dataset. It may also be better to post this question in the SAS/GRAPH and ODS Graphics community, if you haven't already.

Thank you.

Kriss