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One of the items discussed in THEMIS however maybe didn’t have a specific forum post was do we allow events to fall out of observations periods?

Here is what we are currently recommending:

1. Events CAN fall out of observation period. 2. Payer plan period should be used to capture coverage (including partial e.g. Medicare part D) and can overlap with the observation period. 3. Every patient must have at least one observation period.

1. not use time outside of an observation period for identifying people. 2. to ensure quality do not use events outside of an observation period for an analysis. 3. if patients do not meet criteria for observation period (e.g. have partial Medicare D coverage), create an alternative CDM that allows for them to fall in OBSERVABLE_TIME.

Update CDM Wiki for OBSERVATION_PERIOD to discussion in the conventions.


Copying here from Github:

So, we now have two problems with the Drug Eras:

  • Drugs outside the Observation Period
  • Patient reported drugs

I agree with @Ajit_Londhe, and either one should be left out: The former has no reliable capture, later no precise timing. Either way things like Persistence Windows will be meaningless.


I would say as long as the DRUG_START is before the end of the OBSERVATION_PERIOD it should be included. If a drug starts the last day of your OBS_PERIOD but goes for 60 days it shouldn’t be excluded because of that.

From SQL programming perspective, I don’t see how an event can fall outside OBSERVATION_PERIOD. I checked the standard SQL code for OBSERVATION_PERIOD, it uses the MAX(COALESCE(condition_end_date, condition_start_date)), MAX(COALESCE(drug_exposure_end_date, drug_exposure_start_date)) and maximum of other transaction dates. So in theory, all events should fall into the OBSERVATION_PERIOD. The only exception to this is Death. Am I correct or I am missing something?