The 1993-2002 NIS Supplemental Discharge-Level Files are discharge-level files that provide the NIS data user with both the trend weights and data elements that are consistently defined across data years. They are part of a family of databases and software tools developed as part of the Healthcare Cost and Utilization Project (HCUP), a Federal-State-Industry partnership sponsored by the Agency for Healthcare Research and Quality. HCUP databases, tools, and software inform decision making at the national, State, and community levels.
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The NIS is available yearly, beginning with 1988, allowing analysis of trends over time. Analyses of time trends using the HCUP NIS are recommended from 1993 forward. The HCUP National Inpatient Sample (NIS) was redesigned in 1998 and again in 2012 data to improve national estimates. In order to facilitate analysis of trends using multiple years of NIS data, AHRQ developed new discharge trend weights for the 1993-2011 NIS. These weights adjust for changes in the 2012 NIS design and are designed to be used instead of the original NIS discharge weights for trends analysis. For trends analysis spanning 2012 and earlier NIS data, trend weights should be used prior to 2012 data to make estimates comparable to the new 2012 NIS design. The trend weights were developed for trends analysis, but they can be used for all analyses, as is done on the HCUPnet website. The new trend weights replace the earlier NIS Trend Weights that were developed for the 1988-1997 NIS following the 1998 NIS redesign. The report Using the HCUP Nationwide Inpatient Sample to Estimate Trends, available on the HCUP-US website under Methods Series, includes recommendations for trends analysis. The purpose of the 1993-2002 NIS Supplemental Discharge Level-Files is to ease the burden on researchers conducting analyses that span multiple years. These files provide the data user with both the updated trend weights and additional data elements not contained on the original 1993-2002 NIS files, which were added for later years of the NIS through 2002. The following table enumerates the differences in weighted discharges: |
| YEAR | Number of Discharges in the NIS, Weighted | Number of Discharges in the NIS, Weighted with Trend Weight | Difference | HCUPnet Weighted Discharges | Difference | Comment |
|---|---|---|---|---|---|---|
| 1993 | 34,715,985 | 33,736,753 | -979,232 | 33,735,002 | 1,751 | HCUPnet removed outlier records. |
| 1994 | 34,622,203 | 33,149,768 | -1,472,435 | 33,148,180 | 1,588 | HCUPnet removed outlier records. |
| 1995 | 34,791,998 | 33,647,121 | -1,144,877 | 33,644,908 | 2,213 | HCUPnet removed outlier records. |
| 1996 | 34,874,386 | 33,386,097 | -1,488,289 | 33,384,374 | 1,723 | HCUPnet removed outlier records. |
| 1997 | 35,408,207 | 33,232,257 | -2,175,950 | 33,230,554 | 1,703 | HCUPnet removed outlier records. |
| 1998 | 34,874,001 | 33,923,632 | -950,369 | 33,923,632 | 0 | |
| 1999 | 35,467,673 | 34,440,994 | -1,026,679 | 34,440,994 | 0 | |
| 2000 | 36,417,565 | 35,300,425 | -1,117,140 | 35,300,425 | 0 | |
| 2001 | 37,187,641 | 36,093,550 | -1,094,091 | 36,093,550 | 0 | |
| 2002 | 37,804,021 | 36,523,831 | -1,280,190 | 36,523,831 | 0 |
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The NIS Supplemental Discharge-Level files are designed to be merged with the NIS Core files to produce a dataset containing the complete set of variables from both sources. The DVD contains the Discharge-Level data files, documentation, load programs for SAS, SPSS, and Stata, and an example SAS program to merge the NIS Supplemental Discharge-Level Files with the NIS Core Files. The DVD does not include the NIS Core files, which must be obtained separately from the HCUP Central Distributor. |
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There is one NIS Supplemental Discharge-Level data file for each year from 1993 to 2002. No supplemental files were created for later years because 2003 served as the base comparison. The 1993-2002 NIS Supplemental Discharge-Level Files are appropriate for use in conjunction with the NIS data files that are available for purchase through the HCUP Central Distributor. |
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The NIS Supplemental Discharge-Level Files are provided in fixed-width ASCII files. The files require a statistical software package such as SAS, SPSS, or Stata to use for analytic purposes. Load programs for SAS, SPSS, and Stata are provided. |
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The User Guide for the NIS Supplemental Discharge-Level Files contains:
Web Browser Download: Your browser may support loading the User Guides from this Web page. To download the User Guides from this Web page, click on the following links with the right mouse button and select "Save Link As" (Netscape) or "Save Target As" (Internet Explorer). After saving a file, find it by using Windows® Explorer (Windows® 98/95/NT) or File Manager (Windows® 3.x), and then open the file by double-clicking on it.
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HCUP 1993-2002 NIS Supplemental Discharge-Level Files are available from the HCUP Central Distributor. These files are free of charge. Contact the HCUP Central Distributor to obtain your own copy of these files. |
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| Internet Citation: 1993-2002 Nationwide Inpatient Sample (NIS) Supplemental Discharge-Level Files Healthcare Cost and Utilization Project (HCUP). January 2018. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/nation/nis/nistrends2.jsp. |
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| Last modified 1/18/18 |
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