Thank you for your question. For STK-5, hospital arrival is either the time the patient arrives in the ED, or it is the admission time for the inpatient encounter. The numerator is expressed 2 ways using OR statements: OR: "Medication, Administered: Antithrombotic Therapy" <=1 day starts after start of Occurrence A of $EncounterInpatientNonElective. This first statement is to account for a patient who receives antithrombotic therapy <=1day after the start of the non-elective inpatient encounter. OR: "Encounter, Peformed: Emergency Department Visit" satisfies all •<=1 day starts before start of "Medication, Administered: Antithrombotic Therapy" •<= 1 hour ends before or concurrent with start of Occurrence A of $EncounterInpatientNonElective This second OR statement is if the patient has an ED visit that starts <= 1 day before the antithrombotic medication administration, and ends <= 1 hour before or concurrent with the start of the non-elective inpatient encounter. Currently the eCQM does not account for the example you provided above, in which a patient comes in through the ED, goes into observation, then gets admitted as an inpatient. Once the time between the ED visit and the inpatient encounter spans > 1 hour, the patient falls out. This issue will not be addressed until we have a new expression language available. To find more information on this, you can refer to CQM-1608 in JIRA.