Thank you for your question regarding CMS871v4, Hospital Harm - Severe Hyperglycemia. This measure assesses the number of inpatient hospital days for patients age 18 and older with a hyperglycemic event (harm) per the total qualifying inpatient hospital days for that encounter. As this is a ratio measure, the measure includes two measure observations that assess the inpatient hospitalizations identified through the numerator and denominator criteria to return the inpatient hospital days that are ultimately used in the measure calculation. To calculate this ratio of inpatient hospital days, the denominator and numerator first identify the inpatient hospitalizations to be assessed by the measure. The denominator identifies inpatient hospitalizations for patients age 18 and older that end during the measurement period and that (1) have a diagnosis of diabetes that starts before the end of the encounter; or (2) administration of at least one dose of insulin or hypoglycemic medication that starts during the encounter; or (3) presence of at least one glucose value >=200 mg/dL at any time during the encounter. The numerator identifies inpatient hospitalizations with a hyperglycemic event within the first 10 days of the encounter minus the first 24 hours, and minus the last period before discharge from the hospital if less than 24 hours. If a hospitalization does not meet the numerator and/or denominator criteria, it will not be assessed by this measure. Measure Observation 1, associated with the denominator, returns the total number of eligible hospital days of an inpatient hospitalization that meets the denominator criteria and does not meet the denominator exclusion criteria. Measure Observation 2, associated with the numerator, returns the number of hyperglycemic days during an inpatient hospitalization that meets the numerator criteria and does not meet the numerator exclusion criteria. The two measure observations are then used to calculate the ratio of the number of inpatient hospital days with a hyperglycemic (high blood glucose) event over the total number of eligible inpatient hospital days (<= 10 days) for that encounter. Please see the attached example table for an illustration of how the measure observations identify eligible hospital days and hyperglycemic event days in an inpatient hospitalization that meets both the numerator and denominator criteria. Please note that for this measure, hospital days are not defined as midnight-to-midnight but are full 24-hour periods that start at the time of admission to the hospital. And in determining eligible days, this measure does not evaluate the last day if it was less than a 24-hour period. Finally, since the measure does not count any hyperglycemic events that occur in the first 24 hours, Day Index 1 is not considered an eligible hospital day for the Measure Observations. In this example, Measure Observation 1 (associated with denominator) identifies four (4) eligible hospital days of the inpatient hospitalization period. Measure Observation 2 (associated with the numerator) identifies one (1) hyperglycemic event day out of the four eligible hospital days. Therefore, to calculate the measure ratio, Measure Observation 2 (one hyperglycemic event day) is divided by Measure Observation 1 (four eligible hospital days) for a ratio of 0.25. Please refer to the CMS871v4 Measure Flow ( https://nam12.safelinks.protection.outlook.com/?url=https://ecqi.healthit.gov/sites/default/files/ecqm/measures/CMS871v4-eCQMFlow.pdf&data=05%7c02%7cMBauman%40mathematica-mpr.com%7ce1bbe3e9a14b437c43fb08dd83554bbe%7c13af8d650b4b4c0fa446a427419abfd6%7c0%7c0%7c638811124552944189%7cUnknown%7cTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7c0%7c%7c%7c&sdata=xZ7g6RsodJSSyp7QxbMK8TtHa0ULK3SSHt6QQTAvIqg%3D&reserved=0 ) for more information on how this measure is calculated.