EVER since Congress enacted the hospital prospective payment system for Medicare in 1983, diagnostic semantics have come under increasing scrutiny. Under this reimbursement method, hospitals are paid a single, predetermined sum based on the patient's diagnosis-related group (DRG). The DRG system sorts the realm of "diagnoses" into 467 groups. However, the termdiagnosismay be a misnomer. Some of the DRGs may be more appropriately called "symptom-related groups"—chest pain (DRG 143), for example. Others may be labeled "pathology-related groups" (atherosclerosis, DRGs 132 and 133), while still others may be best titled "severity-related groups" (heart failure and shock, DRG 127). This quibbling over the diagnostic lexicon may appear a trivial exercise unless one remembers that the DRG assignment dictates level of reimbursement. Each of the 467 DRGs has its own nationwide relative weight (RW) for reimbursement. Therefore, pecuniary incentives encourage close inspection of diagnostic phrasing to ensure patient allocation to the