OHDSI Home | Forums | Wiki | Github

ATLAS entry event - How to consider entire population?

Researchers
#1

Hello Everyone,

I am trying to create a cohort with people who are not using a particular drug (who do not have any record of a specific drug_concept_id in the drug_exposure table) in ATLAS.

I am not sure how to set up the cohort entry event, I believe I need to consider the entire population in the dataset and then add the inclusion criteria setting the occurrences to “0” for those drugs which I want to exclude. But I don’t see there is a way to add entire population in the cohort entry event.

Can someone guid me how to build a cohort when I want to exclude something from the entire population? Is there a better way to do this in ATLAS? I might even consider using HADES for this if there is a better approach in it.

Thank you so much for your help in advance.

#2

I think this is the wrong approach to thinking about how to define pehotypes (ie: people who do not have something) because there is no index date on which to identify where they had nothing. You can start with a visit and indicate that they should have exactly 0 of something all days before and all days after, but you still started with a positive, not a negative.

To your specific case: the closes representation to your database population is ‘OBSERVATION_PERIOD’. This is because people can have observation periods even without taking any drugs, any conditions, or procedures. Observation period means that this person ‘exists for a given period of time in the data’.

So, start with entry events of ObservationPeriod, but for the same of your DBAs and CPU cycle waste, nest criteria in the Observation Period criteria for the things you want to exclude: Enters the cohort on the start date of their Observation Period, whre the Observation Period has exactly 0 occurrences of Drug X.

t