Thank you for your inquiry specific to CMS871v2 Hospital Harm – Severe Hyperglycemia. The first 24-hour period of the hospitalization begins from the encounter start datetime. The encounter start datetime can be the emergency department (ED) encounter start, the Observation encounter start, or the inpatient encounter start depending on how the patient was admitted to the hospital and if the transition between the end of the ED and/or Observation and start of the inpatient stay is within an hour or less of each other. For example, if a patient came to the ED and was admitted to inpatient, then the encounter start would be the ED encounter. If a patient was a direct admit to inpatient, then the encounter start would be the inpatient encounter start time. Please see these examples to further clarify: -ED encounter on 11/19 starts at 0200 and ends at 0730. Inpatient admission starts on 11/19 at 0900. In this scenario, the 24-hour timeframe begins on 11/19 at 0900. -Observation encounter on 11/19 starts at 0200 and ends at 0830. Inpatient admission starts on 11/19 at 0900. In this scenario, the 24-hour timeframe begins on 11/19 at 0200.   We appreciate your question and feedback and will consider revising the language in the narrative to make this clearer during the upcoming eCQM Annual Update cycle.