Hi,
Iâve taken some time to consider your points. One thing Iâd like to clarify about my position on observational data is that the dates of the facts arenât always when something actually happened, but rather itâs the date that we were informed of the fact. Most of the time, these dates are very close: the date of a measurement is probably the same date that we were informed of this fact; the date of a diagnosis is usually the same that the system is informed.
Consider the case where someone comes to a doctor after suffering for a week with some sort of painful swelling. The doctor concludes that thereâs an infection. Does the doctor put down that the infection started a week ago? The date of the diagnosis of âinfectionâ will be the date the doctor found out about it, not back-filled to some prior date.
But when we get to survey and âhistory ofâ type of facts, I believe this principle holds: when a survey is collected, you know the date the information was collected (ie: made known to the system) but the information within the survey could relate to âcurrent state of patientâ or âsomething that occurred int he pastâ. If itâs current state, then it is an observation on the date of the survey. If it is an observation about the past, then it is a statement about history, but as of the date of the survey. I donât think we should throw this away, but I also donât think we should inject âfactsâ into history since clinical actions taken on a patient didnât actually have that information at the time.
So, getting to your example of survey data: imagine a patient timeline with clinical observations, and in the middle of that timeline the patient answers the survey. Using any index date before the survey would lead you to some clinical conclusions/statements about the characteristics of the patient that would be very different after the survey was performed at an index after the survey. So, donât throw it away, just treat the information as if it was known as of the survey date, using direct concepts as observations if it is current state, and wrap it into a âhistory_of + value_as_conceptâ for those historical cases. in this way, we donât actually need a date of when the actual thing happened in history.
But, if âscope of historyâ is important (as in: recent history, distant history), I think it would make sense to introduce a hierarchy of History Of concepts that allow you to capture the different history contexts, something like:
-> within 5y-> within 1y-> Within 6m -> within 3m -> within 1m
History Of -|
-> after 1m -> after 3m -> after 6mo -> after 1y -> after 5y
The idea of this hierarchy is to allow you to say things like âanything within 5yâ and things coded to 1y, 6m, 3m or 1m are included in the descendants. Same thing with after 1mâŚIf you donât care, just pick all descendants of âhistory ofâ.
Iâd translate things like âat age 65â to one of these buckets, otherwise you need to do a multi-step translation of what the age was relative to the date in order to covert that date into something usable for comparison.
And, what about âfamily historyâ cases? I think youâd solve this the same way: the date of the observation is when it was known, not âthe beginning of timeâ as some people suggest. Clinical decision making is based on the family history based on when this information is known, not retroactively back to the beginning of their patient record.
I think Iâve seen other proposals where âhistory ofâ observations are placed outside of observation periods or at the start of observation periods, but I really donât think this makes sense: If you have a history of smoking, do you really put that record back at your year of birth (if your observation starts at birth)? pretty sure they do not allow smoking infants in the OR. Instead, all of these facts could just be captured at the day they are known in an observation record, and clinical analysis can be performed based on what is known at the time of the index, not what we âthinkâ we might have known based on some date-offset from a survey response (or patient reported history).