​​Thank you for your question on the Safe Use of Opioids measure (CMS 506). An inpatient encounter is identified by the value set "Encounter Inpatient" (2.16.840.1.113883.3.666.5.307). Observation stays are typically coded differently from an inpatient stay, so an observation stay encounter would not be included in the measure. All inpatient stays, as identified by the Encounter Inpatient value set, that end with an opioid or benzodiazepine at discharge should be included in the measure regardless of how a patient came to be admitted to the inpatient setting. In version 5 of the measure, the logic looks at observation stays and emergency department stays immediately prior to the inpatient stay for hospice or palliative care that may exclude a patient from the denominator. No other data from an emergency department visit or observation stay are relevant to the Safe Use of Opioids measure. Please let us know if you have additional questions.