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# PSA: Cohort Criteria with 'Having at least 3 of N criteria'

Hello, Everyone.
During OHDSI 2022 conference, a cohort definition was presented that was used (I believe it was Korea) where the logic was described as very complicated. Although the slide flashed by very quickly, I did manage to catch that the criteria indicated ‘having 3 of the following conditions’ (and I believe the list of things to look for numbered between 7 and 12…not sure exactly).

The view of the cohort definition looked like it was using a very complex arrangement of criteria that I believe was trying to replicate the ‘at least 3 of (10?) of the following…’ logic by using a series of ANDS and ORs… For example, the way you could say having at least 2 of 4 of A,B,C,D could be written as:
(A AND B) or (A AND C) OR (A AND D) OR (B AND C) OR (B AND D) OR (C AND D).

That covers all the combinations of selecting 2 of the 4 A,B,C,D choices.

However, there’s an easier way: You can define 1 group of the 4 conditions, and say 'having at least 2 of the following: (A OR B OR C OR D).

This is what this looks like in atlas:

This also works in cases where one of the things that would qualify you would be a combination: (A AND B) OR C OR D. The ‘group’ of (A AND B) would count as one of the criteria counts in the OR.

Hope this helps!

-Chris

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