In the IHE PCC Technical Framework, the medication entry often has effectiveTime elements that tell you the intended or actual time of use (see yesterday's post for how to use those). But even then, you may not know the dates, but still want to indicate that this is a historical medication.
So a different mechanism is needed to indicate that a medication is currently active, on hold (e.g., blood thinners before surgery), or no longer active. The CCD specification contains a Medication Status entry that can appear within a substanceAdministration or supply act to support this.
The medication status entry looks like this and should appear at the end1 of the substanceAdministration or supply act (with all other entryRelationship elements:
The codes and display names that you can use for this entry are:
|73425007||No Longer Active|
I don't know what the difference between Prior History and No Longer Active are. They are nearly enough equivalent that you should be able to assume that if either of those codes are present, the medication is no longer being used.
1 It need not appear exactly at the end, so long as it is with all the other entryRelationship elements. But if you don't know where to put it, that's the best place for me to tell you, because it will be correct according to the CDA schema.