For the move to CDMv6, perhaps
condition_end_datetime should be not null as consistent with other tables?
drug_exposure_end_datetime is mandatory. This is smart since analysis logic doesn’t have the background necessary to easily know when a drug exposure period has ended, besides guessing that it’s the
start_datetime plus the
days_supply, or failing that, the
start_datetime + 1day. In this case, an ETL process could make a better guess, and this guess can be seen in the database itself.
For other tables,
end_datetime is also mandatory, except for
condition, where it remains nullable. Why? Perhaps a
null ending datetime might indicate a condition isn’t yet resolved and is ongoing? But, there’s a challenge with this. Most of the cohort logic that I’ve reviewed is defaulting a missing
start_date + 1day – it is not defaulting to the last day of the observation period. In other words, the cohort logic doesn’t treat the
null value as an indeterminate interval ending, as is the treatment in the Clinical Quality Language (CQL). Instead, the default logic (making it equal to
start_date +1 day) is applied universally, when other information at the data source might be better equipped to make a more plausible ending value on a case by case basis.