The Healthcare Cost and Utilization Project (HCUP) includes the largest current collection of longitudinal care data in the United States. HCUP consists of several nationwide databases available through the Agency for Healthcare Research and Quality (AHRQ). The databases are publicly available (at a fee) and can be used to identify, track, and analyze national trends in healthcare utilization.
WMed has purchased and currently has access to several of the databases, including:
- National Inpatient Sample (NIS, 1988-2014 & 2016-2021)
- Kids’ Inpatient Database (KID, 2006, 2009, 2012, 2016, & 2019)
- Nationwide Emergency Department Sample (NEDS, 2009, 2012, 2015)
- Nationwide Readmissions Database (NRD, 2012, 2013, 2014)
More information on the HCUP databases can be found on the Healthcare Cost & Utilization Project User Support website.
Access to the data sets available for WMed is overseen by the WMed Data Analytics Services Unit (DASU). Questions on feasibility or availability of data can be sent to dataanalytics@wmed.edu.
All HCUP projects should use the HCUP protocol template. A separate Excel file has also been created to collect International Classification of Diseases (ICD) codes. Directions on how to access the protocol and complete the Excel file are available via PDF or video . Study teams must use this Excel template when submitting ICD codes for a project. It allows for clarity for the biostatisticians building the query and maximizes efficiency. Any questions can be directed to dataanalytics@wmed.edu.
Note: Analysis will not begin for your HCUP project until both documents are finalized and submitted to the Data Analytics Services Unit. Meetings with the biostatisticians will be scheduled as needed.
HCUP Resources
FAQs
- How do I get started with a HCUP project?
All projects should be submitted through the Project Request and Triage Form. For the question, “Is there a data pull?” select Yes. There will then be an option to select “HCUP”. A project initiation meeting will then be scheduled to discuss research questions and feasibility.
- What is NIS?
The NIS (Nationwide Inpatient Sample) is the most popular database currently in use at WMed. The NIS is the largest publicly available all-payer inpatient care database and is published yearly. Unweighted, it contains ~7 million hospitalizations per year; however, the database is built to allow for national estimates. A list of variables for the NIS database can be found here.
- What is KID?
The KID database is very similar to the NIS but contains only pediatric hospitalizations (age less than 21). The KID is published every 3 years and contains ~3 million unweighted pediatric hospitalizations per dataset. A list of variables for the KID database can be found here.
- Can I get access to a HCUP database?
Due to the data use agreement in place with HCUP, only the biostatisticians and the Manager of the Data Analytics Services Unit (DASU) have direct access to the databases. As such, research teams will not have direct access to the database and will only receive aggregate reports related to their research project. Please fill out a Project Request and Triage Form to begin the process.
- What kind of research questions can I answer with HCUP?
The sheer size of the databases allows for looking at certain rarer diagnoses that may not be prevalent in southwest Michigan. The databases can also be utilized for analyzing incidence (including national estimates), trends (of incidence, mortality, etc.), length of stay, and cost of certain diagnoses. The databases also can be used to examine incidence in specific regions of the U.S.
- Can I combine databases?
The different databases cannot be linked. For example, we cannot link hospitalizations between the NIS (Nationwide Inpatient Sample) and the NRD (Nationwide Readmissions Database). An HCUP project can only utilize one of the databases.
- What are the benefits of using HCUP?
- The sheer size of the databases allows for analysis of rarer diseases and conditions that might not be prevalent in Kalamazoo, MI.
- It allows for the ability to analyze trends over years (especially with NIS, as WMed has access to multiple years).
- It can be used to make national estimates.
- It does not require a data pull from outside sources – The databases are queried by the WMed biostatisticians, which can result in quicker data pulls than requesting electronic health record (EHR) data.
- What are the drawbacks of using HCUP?
- Some of the variables are limited. For example, there is no lab or medication documentation. The databases only record billable International Classification of Disease (ICD) or Procedure Coding System (PCS) codes.
- Some of the databases (NIS, KID, NEDS) do not track readmissions.
- There is a significant time commitment up front from study teams to determine which ICD/PCS codes they are interested in looking at.
- The HCUP DUA agreement does not allow reporting counts <11 in any field. As such, the WMed biostatisticians will not report any counts (unweighted or weighted) <11.
- There is not a one-to-one mapping for diagnoses between ICD9 and ICD10; as such, analyzing both can lead to some degree of estimation.
- What are the Elixhauser comorbidity groups and how are they used with HCUP/NIS?
Some comorbidities are already included in the HCUP database. They are classified using the Elixhauser Comorbidity software. The table below contains a list of the variables. Note: Some are only available in ICD9 or ICD10 but not both. If teams would rather use these than find individual ICD codes, they can indicate so in the Excel file; simply put “AIDS - Elixhauser”. The diagnosis codes contained within the groups can be found here.
Diagnosis ICD9 ICD10 Aids Y Y Alcohol Abuse Y Y Deficiency Anemias Y Y Autoimmune Conditions Y Rheumatoid Arthritis/Collagen Vascular Disease Y Chronic Blood Loss Anemia Y Y Lymphoma Y Y Leukemia Y Metastatic Cancer Y Y Solid Tumor Without Metastasis, In Situ Y Y Solid Tumor Without Metastasis, Malignant Y Cerebrovascular Disease Y Congestive Heart Failure Y Y Chronic Pulmonary Disease Y Y Coagulopathy Y Y Dementia Y Depression Y Y Diabetes, Uncomplicated Y Y Diabetes With Chronic Complications Y Y Drug Abuse Y Y Hypertension (Uncomplicated and Complicated) Y Y Hypothyroidism Y Y Other Thyroid Disorders Y Liver Disease Y Y Fluid and Electrolyte Disorders Y Neurological Disorders Affecting Movement Y Other Neurological Disorders Y Y Seizures and Epilepsy Y Obesity Y Y Paralysis Y Y Peripheral Vascular Disorders Y Y Psychoses Y Y Pulmonary Circulation Disorders Y Y Renal Failure Y Y Peptic Ulcer Disease Excluding Bleeding Y Y Valvular Disease Y Y Weight Loss Y Y - Where can I find ICD or PCS codes?
The DASU recommends using this website for determining ICD codes: https://www.icd10data.com/ICD10CM/Codes.
Again, only codes with the green arrows are searchable within the HCUP databases. This website also converts back to ICD9, if that is needed for a project.
Recent WMed Publications Using HCUP
A full list can be found in the WMed Library.
- Costa Filho FF, Buckley JD, Furlan A, Campbell S, Hickok K, Kroth PJ. Inpatient complication rates of bronchoscopic lung volume reduction in the United States, CHEST (2024), doi: 10.1016/j.chest.2024.08.012.
- Lima NA, Cwikla K, Byers-Spencer K, Crumm I, Patel D, Huffman C, McGoff TN, Young J, Melgar TA, Helmstetter N. Malignant cardiac neoplasms and associated malignancies over 16 years in the USA, Journal of Cardiology (2024), doi: 10.1016/j.jjcc.2023.09.004.
- Lima NA, Byers-Spencer K, Cwikla K, Huffman C, Diaz M, Melgar TA, Helmstetter N. Benign Cardiac Neoplasms in the United States: A Thirteen-Year Review, Journal of Cardiology (2021), doi: 10.1159/000519290.
- Lima NA, Patel DA, Sundaram N, De Castro RL, Huffman C, Diaz M, Linares ST, Melgar TA. Hospital admissions for mitral stenosis in pregnancy in the United States: a thirteen-year analysis, American Journal of Cardiovascular Disease (2023).
- Sieloff EM, Rutledge B, Huffman C, Vos D, Melgar T. National trends and outcomes of genetically inherited non-alcoholic chronic liver disease in the USA: Estimates from the National Inpatient Sample (NIS) database, Gastroenterology Report (2021), doi: 10.1093/gastro/goaa091
- Maravelas R, Melgar TA, Vos D, Lima N, Sadarangani S. Pyomyositis in the United States 2002-2014, Journal of Infection (2020), doi: 10.1016/j.jinf.2020.02.005
- Sieloff E, Ladzinksi A, Alcantara Lima N, Vos D, Boamah H, Melgar T. Hospitalizations for tuberculous peritonitis in the United States: Results from the national inpatient sample database from 2002 to 2014, International Journal of Myobacteriology (2020), doi 10.4103/ijmy.ijmy_68_20
- Lima NA, De Castro RL, Huffman C, Diaz M, Lima CCV, Schauer M, Linares ST, Melgar TA. Hospital admissions for aortic stenosis in pregnancy in the United States – A thirteen year analysis, American Journal of Cardiovascular Disease (2020)/