The QDM guidance regarding cumulative medication duration states that it should generally be calculated as the number of doses in the interval of interest, divided by the doses per day. The actual duration (start date to end date) of a "Medication, Active" entry should not be a part of the calculation-- only the metadata of the order should be used (quantity, dosage, refills, etc). Regarding #1, there still could be a problem if you are using the "during" timing relationship. If you say something like Sum > 180 day(s) of: "Medication, Active: MyMed (cumulative medication duration)" during "Measurement Period", then if the Medication, Active has no end date it will not be captured in the calculation (since we can't determine that it is during the measurement period). Instead, you could potentially use starts during – but be aware that this will capture (and calculate) entries that overlap past the measure period end. Another possible approach would be to do the calculation on a different datatype (like Medication, Order) if you know it's more likely to have an end date. Regarding #2, as noted above, in the case of CMD the duration should be based on order data, not on the start/end times of the "Medication, Active" event. Unless an order has unlimited refills, it shouldn't calculate the CMD based on "forever"-- it will calculate out as far as the refills go.