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; (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. Measure observation 1, associated with the denominator, returns the total number of eligible hospital days of inpatient hospitalizations that meet the denominator criteria and do not meet the denominator exclusion criteria. Measure observation 2, associated with the numerator, returns the total number of hyperglycemic days during inpatient hospitalizations that meet the numerator criteria and do 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 for an illustration of how the measure’s performance ratio would be calculated using the example numbers you provided in your inquiry.