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Data Requests and Forms


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. 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 MedCHi 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

As part of its broad disclosure responsibilities, the commission makes available several non-confidential, patient-level datasets to the public. Descriptions of the datasets are below.

Basic File: 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 File: 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.

Revisit Segment: 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: This segment 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:

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 (click here Public Use Data Request Form and choose “Public Use Data Request”).

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

Certification of Data Destruction Form

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. User’s requesting aggregated data must complete and submit an application (click here Statistical Request Form and choose “Statistical Request”). 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).

In addition, the Statistical Data Use Agreement is required by all users requesting the aggregated data tables pertaining to the use of medical information, specifying compliance with HSCRC data use restrictions, as well as, state law and regulations.

Statistical Data Use Agreement

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