Thank you for your inquiry regarding CMS816v4, Hospital Harm – Severe Hypoglycemia, and CMS871v4, Hospital Harm – Severe Hyperglycemia.   Specific to CMS816v4, the numerator is constrained to severe hypoglycemic events, in which the logic evaluates that a glucose test was administered with a result less than 40 mg/dL AND a hypoglycemic medication was administered within 24 hours before the start of the hypoglycemic event. To safeguard the numerator from potentially aberrant results, the logic also evaluates to ensure there was no subsequent repeat test for glucose with a result greater than 80 mg/dL within five minutes or less from the start of the initial glucose with a result less than 40 mg/dL. If the logic observes this criteria, then the inpatient hospitalization will not meet the numerator criteria; however, the inpatient hospitalization would remain in the denominator, since the qualifying encounter entailed receipt of a hypoglycemic medication. Specific to CMS871v4, while there is no clinically accepted cutoff for severe hyperglycemia, studies have used thresholds of >140, >180, >300, >350, and >400 mg/dL, among other values (CMS871v4: Hospital Harm - Severe Hyperglycemia). In CMS871v4, the measure’s numerator looks for qualifying inpatient hospitalizations with a hyperglycemic event, defined as either a day with at least one glucose value of greater than 300 mg/dL OR a day where a glucose test and result was not found, and it was immediately preceded by two contiguous, consecutive days where at least one glucose value during each of the two days was greater than or equal to 200 mg/dL. In regard to the first part of the numerator criteria, clinical experts have agreed that a blood glucose test result higher than 300 mg/dL signals a hyperglycemic harm that is unlikely to be due to an aberrant test result. While a high blood glucose test result may have a 10 to 15% deviation from the patient’s actual blood glucose value, this difference would not affect how a patient’s care is managed, as it would if a low blood glucose test result were returned. Additionally, even if a blood glucose test result of 301 mg/dL had a maximal deviation of 15% compared to the patient's actual blood glucose value, the patient would still be experiencing a hyperglycemic harm. For example, a patient with a blood glucose test result of 301 mg/dL could have an actual blood glucose value of anywhere between 255 mg/dL to 345 mg/dL; any value in this range would be considered to be severe hyperglycemia, as defined by experts and several studies. Additionally, as hyperglycemic patients are generally asymptomatic, there is typically no clinical basis for doubting a high numeric result of a blood glucose test. Regarding the second part of the numerator criteria, the measure assumes that if a patient had a daily blood glucose test result of greater than or equal to 200 mg/dL for two continuous, consecutive days, these successive high blood glucose test results are unlikely to be due to aberrant results.