NITOS 4.0 is a significant expansion of prior versions of the tool. In addition to continuing to reflect the most current radiology practice procedures available in claims databases, it has also been expanded to include additional data sources. To read the methodology for prior versions of NITOS, click on the following link: Prior NITOS methodology.
In brief, NITOS classifies claims billed by radiologists into a four-digit code in which each letter of the code directly categorizes the procedure by one of the following descriptors: 1) if it is invasive or non-invasive; 2) the imaging modality; 3) the body region imaged; and 4) the focus (e.g. body system) within the region. These codes can be merged into datasets to allow consistent identification or stratification of imaging procedures into clinically relevant categories for research and analytics.
In the past, the NITOS codes were based, in part, on procedures found in the CMS Medicare Physician/Supplier Procedure Summary. The Physician/Supplier Procedure Summary (PSPS) file is a summary of calendar year Medicare Part B carrier and durable medical equipment fee-for-service claims. The PSPS does not include Medicare Advantage claims. PSPS limited datasets with 100% of Part B procedures (versus the publicly available censored version) were used to create NITOS.
Methodological Process
The first step in the methodology was to identify all procedure codes (HCPCS), in the PSPS, billed between 2000 and 2019 for which at least one claim was filed by a radiologist (defined as any physician listed as a diagnostic radiologist, interventional radiologist, or nuclear medicine physician).
The list of HCPCS codes obtained from the 2000-2019 PSPS became the base against which codes from other data sources were compared to.
NITOS codes were newly updated in 2021 to be more inclusive of other data sources. This was done in the second step of the methodology where additional data sources were searched to find “new” codes not included in the 2000-2019 PSPS base file. The additional data sources searched were:
– The 2012-2018 CMS Medicare Physician and Other Supplier (PUF) file: The PUF file provides information on services and procedures provided to Medicare beneficiaries by physicians and other healthcare professionals. Using the 2012-2018 PUF files, a list of HCPCS codes performed by interventional, diagnostic, and nuclear medicine radiologist was created.
– The 2013-2019 Physician and Other Practitioner file: The Physician and Other Practitioner file provides information on services and procedures provided to Original Medicare (fee-for-service) Part B (Medical Insurance) beneficiaries by physicians and other healthcare professionals. The Physician and Other Practitioner file is very similar to the PUF file but includes updates in the methodology*. Using the 2013-2019 Physician and Other Practitioner files, a list of HCPCS codes performed by interventional, diagnostic, and nuclear medicine radiologist was created.
– The Restructured BETOS Classification System (RBCS): The RBCS is an updated version of the original Berenson-Eggers Type of Service (BETOS) classification system created in the 1980s. The RBCS is a taxonomy for healthcare services that allow for the grouping of Medicare Part B services into categories and subcategories. Using the RBCS, a list of HCPCS codes with a RBCS Category of “I” (imaging) was created.
– American College of Radiology internal resource: This is an internal document containing a list of procedures specifically performed by Radiologists.
The list of procedural codes from each of the above sources was compared to the HCPCS codes obtained from the 2000-2019 PSPS. Any codes not included in the PSPS list were retained and added to that list.
This remaining list of procedure codes was then compared to NITOS 3.0. Any code already included in NITOS 3.0 was deleted. In addition, any code that had been previously rejected for NITOS (from the 2015-2017 PSPS) was deleted from this list. The final set of codes that remained were only the new codes from the various sources that had not previously been reviewed.
The final code list contained nearly 3,000 new codes obtained from the PSPS, PUF, Physician and Other Practitioner, Restructured BETOS, and internal sources.
This final list of procedural codes was then analyzed by an expert radiologist panel to determine which codes represented radiology procedures and should be retained for NITOS and the associated NITOS mappings. The radiology procedures are first classified as invasive or non-invasive; the non-invasive procedures are then further classified into modality, body region, and focus. The HCPCS codes that were retained and mapped were added to the NITOS 3.0 list of HCPCS codes and was renamed NITOS 4.0.
Changes in mapping to particular codes
It is important to note that several prior codes (found in NITOS 3.0) were re-mapped:
– HCPCS code 70496 (Ct angiography head Ct angiography, head CT angiography head) was revised from N326 (denoting a non-invasive CT scan performed on the head/neck region) to N316 (denoting a non-invasive CT scan performed on the brain).
– HCPCS codes 73500, 73510, 73520, 73530 (all representing x-ray exams of the hip) were changed from N774 (denoting a non-invasive radiography/fluoroscopy image performed on an extremity) to N764 (denoting a non-invasive radiography/fluoroscopy image performed on the abdomen/pelvis).
*NOTE: Personal email communication from CMS has stated that the Physician and Other Practitioner file includes an updated methodology compared to the PUF file. However, CMS has not yet published how the methodologies differ between the two data sets.