Differences and Importance of IPPS, OPPS, MPFS and DMEPOS The inpatient prospective payment system (IPPS) is a payment system that includes the cases of diagnosis-related groups (DRGs) as acute care hospital inpatients. It is based on resources that are used to treat Medicare recipients in those groups. Each DRG has a payment weight assigned to it, based on the average cost of treating patients in that DRG. IPPS plays an important role in deciding all hospital costs including the costs of all devices for treating the patient during a particular inpatient stay (CMS. Gov, 2012). On the other side, the outpatient prospective payment system (OPPS) is regulated for different outpatient service groups as ambulatory payment classifications (APCs). Outpatient services in each APC are similar in terms of clinical aspects and required resources. In addition, the APC payment rate for each group is wage adjusted to justify geographic differences and applied to all services in the group. In this, hospitals get a fixed amount for all outpatient services based on ambulatory payment classifications. Apart from this, Medicare uses it to reimburse physicians and other health care providers for the services and items that are not part of prospective payment systems (Herbert, 2012). A medicare physician fee schedule (MPFS) determines the payment rates for physician and therapy services that are based on relative value units, conversion factors and geographic practice cost indices. Durable medical equipment, prosthetics, orthotics and supplies (DMEPOS) is related to reimbursement rates for these certain items to suppliers that ensure accessing a high quality of these items to the patients. It includes several payment regulations governing the supply of DMEPOS items for Medicare beneficiaries. It presents the procedure of supplier enrollment, authorization and