CMSTRTPT, CMSTTPT, CMENRTPT and CMENTPT may be populated as necessary to indicate when a medication was used relative to specified time points.
For example, assume a subject uses birth control medication.
The subject has used the same medication for many years and continues to do so.
The date the subject began using the medication (or at least a partial date) would be stored in CMSTDTC.
CMENDTC is null since the end date is unknown (it hasn’t happened yet).
This fact can be recorded by setting CMENTPT=”2007-04-30” (the date at the last visit) and CMENRTPT=”ONGOING”.