The Procedure Classes tool facilitates health services research by allowing the researcher to determine (1) whether a procedure is diagnostic or therapeutic, and (2) whether a procedure is expected to be performed in an operating room. The Procedure Classes assign all ICD-10-PCS or ICD-9-CM procedure codes into one of four categories:

• Minor Diagnostic: Non-operating room procedures that are diagnostic (e.g., ICD-10-PCS code B244ZZZ, Ultrasonography of right heart; ICD-9-CM code 87.03, CT scan of head)
• Minor Therapeutic: Non-operating room procedures that are therapeutic (e.g., ICD-10-PCS code 02HQ33Z, Insertion of infusion device into right pulmonary artery, percutaneous approach; ICD-9-CM code 02.41, Irrigate ventricular shunt)
• Major Diagnostic: All procedures considered valid operating room procedures that are performed for diagnostic reasons (e.g., ICD-10-PCS code 02BV0ZX, Excision of superior vena cava, open approach, diagnostic; ICD-9-CM code 01.14, Open brain biopsy)
• Major Therapeutic: All procedures considered valid operating room procedures that are performed for therapeutic reasons (e.g., ICD-10-PCS code 0210093, Bypass coronary artery, one site from coronary artery with autologous venous tissue, open approach; ICD9-CM code 39.24, Aorta-renal bypass).

Beginning with the Procedure Classes Refined for ICD-10-PCS version 2021.1, the Procedure Classes definition of major surgeries is aligned with the definition of an operating room procedure used by the AHRQ Quality Indicators. Prior to version 2021.1, the Procedure Classes definition of major surgeries was based on the list of operating room procedures used for the Medicare Severity-Diagnosis Related Groups (MS-DRGs).

The availability of the Procedures Classes on the HCUP databases varies across data years:

• Starting in data year 2020, the Procedure Classes are available on all HCUP inpatient databases as the data element array PCLASSn and are based on ICD-10-PCS coding.
• For data year 2019, the Procedure Classes are only available on the HCUP nationwide inpatient databases as the data element array PCLASSn and are based on ICD-10-PCS coding.
• From data years 2016-2018, the Procedure Classes were not included on the HCUP databases because the ICD-10-PCS version of the tool was considered in beta status.
• Prior to data year 2015 quarter 4, the Procedure Classes were stored in the data element PCLASSn and based on ICD-9-CM coding.

For more information, please refer to the Procedure Classes Refined for ICD-10-PCS page of the HCUP-US website under Tools & Software.