The Centers for Medicare and Medicaid Services (CMS) maintain a list of relative value weights (RVUs) for inpatient hospital care. These RVUs, known as the Diagnostic Related Group (DRG) weight, are based on the primary diagnosis when the patient enters the hospital. Some of the DRG groups have been discontinued over time, while others have been added. This reflects changes in morbidity and technology. Therefore, it is important to make sure that the DRG weight file is the same year as the utilization data that you are using.
CMS changed the DRG system in 2008 to MS-DRG. The new MS-DRG has more categories and splits apart old groups into new groups. Hence the new systems is not backwards compatable.
The DRG relative value weight can be found on CMS' web site. CMS provides the historical DRG weights back to 1983, but this historical file is a text table that is relatively challenging to use; HERC has cleaned these data and put them into a Stata file, available upon request (1983-2007 in one file and 2008 onward in another). DRG's weights can be merged to a utilization file using the DRG number. Note, to be able to use the DRG weights, your dataset must have DRGs. The DRG weight file also includes a DRG-specific average length of stay and geometric mean length of stay. See the CMS web site for the most recent DRG weight file.