Which code set would typically be used to report a hospital's case mix index?

The Diagnosis Related Group (DRG) code set is the foundation for calculating a hospital's case mix index (CMI). CMI is a measure that reflects the diversity and intensity of patient care within a hospital, and it is a critical element for understanding hospital reimbursement in the United States. The DRG classification system categorizes patients based on diagnoses, procedures performed, and other factors, which helps in determining how much a hospital will be reimbursed for care rendered.

By using DRGs, hospitals can analyze the types of cases they handle, with each DRG corresponding to a particular level of resource utilization. This data is essential for hospitals when assessing their case mix, evaluating clinical performance, and adjusting for differences in patient populations. Hence, the use of DRGs establishes the appropriate context for measuring CMI, which is primarily focused on overall patient acuity and resource use.

While the other options have their own specific functions—ICD-10 codes classify diseases and can support reporting and coding for various services, CPT codes are used to report outpatient services and procedures, and HPU codes are not a standard industry-recognized code set—they do not serve the specific purpose of calculating a hospital's case mix index. Thus, DRGs are the correct and