Final answer:
DRGs were the first system to measure a hospital's case-mix complexity, categorizing hospitalization costs based on illness or procedure, its severity, and patient's health status.
Step-by-step explanation:
Diagnosis-Related Groups (DRGs) were indeed the first system designed to measure a hospital's case-mix complexity. The statement that DRGs were the first system to allow the measurement of a hospital's case-mix (CM) complexity is True. DRGs are a way to categorize hospitalization costs and determine how much to pay for a patient's hospital stay. They take into account the nature of the illness or procedure, the severity of the illness, and the patient's health status to assign a category which is used as part of the hospital's case-mix analysis.