What sets apart the Outpatient Prospective Payment System (OPPS) from IPPS?

• A. OPPS pays per hour of service.
• B. OPPS uses DRGs.
• C. OPPS pays for outpatient services using Ambulatory Payment Classifications (APCs) rather than DRGs.
• D. OPPS reimburses hospitals based on charge-master lists.

Answer: (C)

What sets OPPS apart is how outpatient hospital services are grouped for payment. In the outpatient prospective payment system, payments are made using Ambulatory Payment Classifications (APCs), which cluster together outpatient services that are clinically similar and consume similar resources. Each encounter may trigger one or more APC-based payments, and the rates are fixed for those classifications, with possible adjustments for drugs, devices, and outlier cases. In contrast, inpatient stays are reimbursed under the Inpatient Prospective Payment System using Diagnosis-Related Groups (DRGs), which classify a hospitalization by diagnosis and procedures to determine a single prospective payment per admission. So the defining difference is APC-based payments for outpatient services versus DRG-based payments for inpatient stays.