​​Hospital Data and Reporting


Clinical Public Use Data Requests


By legislative mandate (COMAR 10.37.06 and COMAR 10.37.04), acute care hospitals in Maryland are required to submit confidential patient-level administrative data (referred to as “case mix data”) on all discharges and visits to the Commission.  As part of its broad disclosure responsibilities, the Commission makes available several non-confidential, patient-level datasets to the public. Descriptions of the data, available datasets, and instructions for access can be found below.
The case mix data includes the following information:​


• Patient identifiers (Medical Record Number, Patient Account Number and Unique Patient ID (EID)) *
• Physician identifiers (National Provider ID (NPI) and Masked MedCH​I ID*)
• Date of birth*
• Sex​
• Race and ethnicity
• Country of birth and preferred spoken language
• Residency (zip code and derived county code based on reported zip code)
• Marital status


• Payer source
• Total charges • UB04 billing information


• Dates of service*
• Principle and secondary diagnosis and procedure codes
• Source and nature of admission
• Discharge status of patient
• Types of services provided
• Flag for diagnosis present on admission (POA)

The inpatient and outpatient data sets are abstracted from the medical record of each of the state’s approximately 700,000 inpatient discharges and 5.7 million outpatient visits annually. Hospitals report clinic, surgery and emergency room data as part of the outpatient dataset.

Available Datasets for Public Use​

Basic Files: This dataset includes inpatient and outpatient case-mix patient demographic data (excluding certain Protected Health Information (PHI) indicated by “*” above), diagnosis and procedure coding, payer source, and total charges. This data has been edited by the State’s data processing vendor, but not processed through any 3M groupers.

Basic Grouped Files: This dataset includes all variables that are included in the Basic File, with additional clinical groupings of clinical codes derived by 3M grouping software (see links below for more information of grouping software). The inpatient data is grouped in the latest version of 3Ms APR-DRG grouper. The outpatient dataset is grouped in the latest version of 3Ms EAPG grouper.

Descriptions of the variables contained in each dataset are here:

Public Use Inpatient Data Dictionary​ (updated January 2024)

Public Use Outpatient Data Dictionary​​​​​ (updated January 2024)​

Market Shift (MS): This dataset includes inpatient and outpatient variables that are processed through 3M's APR-DRG and EAPG groupers, respectively . It is used in the development of the market shift adjustment, which in turn provides the criteria to reallocate funding to account for shifts in cases between regulated hospitals.

Weight Creation & Development (WCD): This dataset and SAS programs are available for users interested in replicating the outpatient weights calculation methodology used by the HSCRC. The outpatient dataset is grouped using the latest version of 3M's EAPG grouper.

Uncompensated Care (UCC): The UCC Write-off Public Use dataset contains unique patient-level information obtained from the Uncompensated Care Write-off data, as well as, from the inpatient and outpatient confidential datasets submitted to the Commission for the current fiscal year. The data is intended to be used strictly for modeling, evaluation and estimating Maryland hospitals uncompensated care amounts to be built prospectively into rates for the upcoming fiscal year.

 Inpatient & Outpatient (ECMAD): The Equivalent Case-Mix Adjusted Discharges or "ECMAD's" dataset includes all Basic File variables, with additional variables reflecting the grouping of clinical codes by 3M (TM) grouping software and ECMAD weights assigned to the visits. Please see the links below for more information regarding the grouping software. 

The inpatient data are grouped using the latest version of the 3M (TM) APR DRG grouper. The outpatient dataset is grouped using the latest version of the 3M (TM) EAPG grouper. The inpatient data also contain outpatient records for observation stays greater than or equal to 24 hours and outpatient records where the high type EAPG is 47, knee replacement. The outpatient data is supplemented with a second dataset with the ECMAD assigned to services provided on each service date during the outpatient visit and other Key Variables used by the HSCRC in computing the Market Shift reports. A key to join or merge this supplemental dataset with the outpatient dataset is included.

ECMAD Data Dictionary (updated July 2023)

​Revisit Files: This dataset contains 3 files (Inpatient, Outpatient, and Outpatient Observation) and includes variables to track admissions of the same patient across settings of care (inpatient and outpatient) and across hospitals. The unique patient ID is also consistent across multiple years to enable users to calculate trends. The inpatient file includes variables from the latest version of the 3M PPC grouper, Preventable Quality Indicators (PQI) flags, and 30-day readmission flags (with and without planned admissions). The outpatient observation file includes only observation cases with stays longer than 24 hours, grouped with the latest version of the APR-DRG grouper. These records are excluded from the outpatient file to avoid duplication of visits.

Please note: The Revisit files may be not requested for commercial purposes (see “Requesting Datasets” section for more information) (available beginning with FY 2013 data). 

Descriptions of the variables contained in each dataset are here:

Revist Inpatient Data Dictionary (updated July 2022)

Revisit Outpatient Data Dictionary​​ ​(updated July 2022)

 Access to Public Use Datasets

Requesting Di-identified Patient Level Datasets

Access to the public datasets described above requires the submission of an application to the HSCRC. Users may request HSCRC data for purposes that support commercial applications, research, studies, or projects referenced in the Application, which has been determined by HSCRC to demonstrate potential to improve the quality of care for Marylanders or reduce the health expenditures, including payment related projects. The uses for the Revisit Dataset are more limited and may be requested for non-commercial purposes only. 

All requests are reviewed by the HSCRC Review Board, which makes the final decisions on the release of the public datasets. The review process may take up to 30 days from submission of the complete letter of request and supporting materials to the Commission for consideration.

The Public Data Use Agreement must be signed by all users of the public data files. A data use agreement pertaining to the use of medical information, specifying compliance with HSCRC data use restrictions, as well as, state law and regulations, must be signed each year. To request the Public Use Files (Basic, Grouped, ECMAD,Revisit, MS, WCD or UCC) (click here) Data Request Form​​​.​​​​ ​

Additionally, consultants using the Inpatient & Outpatient confidential HSCRC Grouped data on behalf of Maryland Hospitals, will use this form (click here)Consultants Data Request Form and DUA​​​​​.​​​

Once the data use agreement expires, requestor must either reapply to continue to use the data or destroy the data. Once the data is destroyed, requestors must submit the Certification of Data Destruction Form​ to: hscrc.data-requests@maryland.gov​​.

Requesting Aggregated Data Tables

The Commission can also provide custom aggregate or statistical datasets for public use. Examples of some aggregated or statistical requests include average length of stay for patients with certain insurance carriers, average charges by hospital, and number of discharges with a specific diagnosis. Users requesting aggregated data must complete the HSCRC's data request application registration form and submit a data request. Please click on this link to start the process: Data Request Application Registration ​
In your request, please specify the purpose of the request, time periods, population, and data source. Please note that ten (10) or less observations will not be reported to protect the identity of patients in small cells.​

Requests that are not complete will not be processed. ​ Please allow 4 weeks for HSCRC staff to review and process your request. If the requested data is not readily available, staff may refer your request to our data processing vendor (processing fees may apply).

For more information on 3M grouper software and AHRQ PQI and Revisit Methodology, see the links below.

3M APR-DRG Grouper

3M EAPG Grouper

3M PPC Grouper


AHRQ HCUP Revisit Methodology Documentation


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