The All-Payer Severity-adjusted DRGs (APS-DRGs) are assigned using software developed by HSS, Inc. This severity measure includes the APS-DRG group number and weights developed using the NIS for mortality, length of stay, and total charges. The prefix "APSDRG" has been included in the data element names to distinguish APS-DRG measures from other HCUP data elements. For more information, please refer to the following documents available on the NIS Documentation CD-ROM and on the HCUP User Support Website (www.hcup-us.ahrq.gov):

• Overview of Severity Systems
• APS-DRGs V20 Definitions Manual
• APS-DRGs V20 Weights Manual