@novinosrin @ballardw Yes, I would like the final expected output to include a variable (e.g., newvar) for each patient indicating whether any diagnosis within a specified group of diagnoses (let's say A, B, C, or D) meets the condition above. For example, if diagnosis A meets the condition for patient 1 and diagnosis B meets the condition for patient 3, then newvar=1 for both patients. So something like this: Patient_ID diagnosis diagnosis_date newvar 1 A 07JAN2015 1 2 X 23FEB2017 0 3 B 02JUN2016 1 ..... @ballardw, yes- your example would meet the 90 day rule since there are two occurrences of the diagnosis, and one occurrence (14Apr2015) is more than 90 days than another occurrence (07JAN2015). Thank you both for the help!
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