Understanding the Current Procedural Terminology (CPT) Coding Framework for COVID-19 Diagnostics

Status August 31, 2020

by Joe Lennerz M.D. Ph.D., Massachusetts General Hospital/Harvard Medical School, Department of Pathology, Center for Integrated Diagnostics, Boston, MA

Why is this relevant?

The need for diagnostic tests in the COVID-19 pandemic continues to outpace test availability. At the same time, financial sustainability is paramount. Reimbursement is a massively complex puzzle and billing codes are only one important piece; however, this is not the time to make coding errors.

The increasingly complex field of COVID-19 laboratory diagnostics is mirrored in continuously evolving coding updates. These updates are created to streamline our ability to accurately reflect medical services to overcome financial and business challenges during the COVID-19 pandemic. Thus, correct billing practices and in particular accurate procedural coding emerges as one seemingly small - yet critical aspect. Simply put:

"With all the uncertainties imposed by the COVID-19 pandemic, you better get your CPT codes right"

Notably, the currently implemented CPT codes follow a distinct and very logical framework. Understanding this framework might help to overcome specific coding questions in challenging cases and improve overall billing practices related to COVID-19. This article outlines the current procedural terminology framework related to COVID-19 diagnostics.

Introduction

Current procedural terminology (CPT) codes are designed, released, and carefully maintained by the American Medical Association (AMA).

Similar to ICD-10 coding, CPT codes identify the rendered medical services (i.e., procedures). The AMA CPT Editorial Panel is addressing the rapidly evolving laboratory testing for COVID-19. The CPT Editorial Panel did a phenomenal job to quickly develop and implement relevant codes. Nonetheless, the overall organization with parent codes, codes that are out of numerical order, monthly AMA updates, and adoption of new proprietary laboratory analysis (PLA) codes can be confusing.

What ranges are relevant?

The CPT codes for pathology and laboratory procedures ranges from 80000–89398. There are many subgroups in this range – for example, surgical pathology is 88300–88399 and for COVID-19 diagnostics two specific ranges are particularly relevant: microbiology 87001–87999 and immunology 86000–86849. So far, all new codes for COVID-19 diagnostics are in these two microbiology and immunology ranges.

cpt Assistant as a reliable source for official definitions and descriptions

The cpt Assistant is an official source for CPT coding guidance and there have been a total of 5 special editions (March, April, May, June, and August of 2020) that introduce the coding framework for COVID-19 diagnostics.

#1 "The cpt Assistants, released by the AMA are the most up-to-date source of reliable information about COVID-19 CPT codes "

Each cpt Assistant is a .pdf document that includes the specific alphanumeric code, the code descriptor, a formal description of the procedure, and one or more clinical examples. Take a look at the August update here.

Towards the COVID-19 CPT code framework

The diagnosis of COVID-19 is based on the integration of clinical and laboratory data. One can consider the various biomarker molecules (=analuytes) related to COVID-19 diagnostics to fall into two broad group: (1) those coming from the virus (SARS-CoV-2) and (2) those biomolecules the human body produces as a response to a pathogen. Now we have to merge these 2 groups with the available assays.

#2 "There are currently four types of COVID-19 diagnostic tests: genetic tests, antigen tests, antibody tests, and neutralization assays"

In other words, the CPT billing logic follows a combination of biological and assay-related principles. Let's start with virus-related analytes.

Virus-related Analytes

Before looking closer into the specific CPT codes, let's reflect on the applied logic of virus-related analytes.

#3 "Virus-related tests are based on detecting viral RNA or a viral protein"

There are two assays assessing these analytes: virus-specific PCR and detection of virus-specific antigens tests.

Polymerase Chain Reaction (PCR)

Genetic tests targeting SARS-CoV-2 specific viral RNA components (=PCR) look for the virus’s RNA in a nose or throat swab, or in saliva samples. The most common type is a polymerase chain reaction (PCR) test. WHO and the Centers for Disease Control and Prevention (CDC) consider PCR tests as the “gold standard” of SARS-CoV-2 testing. These tests are run by laboratories at hospitals, universities, and public health agencies.

#4 "PCR is coded as CPT 87635: Infectious agent detection by nucleic acid (DNA or RNA); severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]), amplified probe technique

PCR reactions can be performed within hours; however, require extraction of nucleic acids or at least disruption of the viral capsule. Turn-around times are typically 12 hours. The CPT code is 87635.

Detecting of Virus-specific Proteins

Antigen tests look for specific proteins on the surface of the virus. Antigen tests can be done more quickly — with results in as little as 15 minutes — using saliva or a nasal swab. Like PCR tests, antigen tests show whether someone has an active infection. 

#5 "CPT 87426 is used to code for Antigen tests: Infectious agent antigen detection by immunoassay technique, (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], immunochemiluminometric assay [IMCA]) qualitative or semiquantitative, multiple-step method; severe acute respiratory syndrome coronavirus (eg, SARS-CoV, SARS-CoV-2 [COVID-19]) 

Turn-around times are ~15 min to 2 hours. The applied CPT code is 87426. Although antigen tests are faster and the number of tests being run can be easily scaled up, they have a high false-negative rate — with as many as half of negative results being inaccurate.

These two assay types (PCR and antigen tests) are shown on the left side of the following figure "Viral Components as Analytes".

The Current CPT Framework for COVID-19 Diagnostics

Coding for tests assessing the "Human Reaction (Antibodies)" to the SARS-CoV-2 (right side of the above figure) is a bit more complex. ...just like the human reaction itself....

Assessing the Human Serologic Response

Antibody tests are blood tests that look for signs that a person has had an prior infection with the virus and had an immune response. The immune system start producing antibodies (against the virus) and these can be detected in the blood. These assays have various names: serology, antibody testing, lateral flow assay (LFA), enzyme-linked immunosorbent assay (ELISA) and many others. Importantly, these tests detect a prior infection and are not used to diagnose an active infection. Specifically, these assays measure whether the patient has antibodies in the blood that can bind to proteins of the SARS-CoV-2 virus (e.g. to SARS-CoV-2 spike protein). Depending on the technology of the assay the turn-around times can be between 15-30 minutes for lateral flow assays or hours to a whole day for ELISA.

#6 "Antibody detection technologies differ in test complextiy - therefore, there are two separate CPT codes for the detection of anti-SARS-CoV-2 antibodies: 86328 and 86769".

The official description of the procedure for "small" or single-step CPT 86328 contains: "A reagent strip cartridge (...) is removed from its sealed container. (...) the patient's blood sample is added to the specimen well, followed by specimen diluent. (...) the specimen is read optically (...). Results are interpreted and reported". This description matches, for example, a single-step lateral flow assay (LFA). Note that the long descriptor for CPT 86328 contains another CPT code - effectively intended as a comment that another CPT code is applicable for mutli-step methods.

#7 "CPT 86328 is applied for single-step antibody assays (e.g. lateral flow assays): Immunoassay for infectious agent antibody(ies), qualitative or semiquantitative, single-step method (eg, reagent strip); severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]) (For severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] [Coronavirus disease {COVID-19}] antibody testing using multiple-step method, use 86769)

In contrast to the single-step method, the procedural description for CPT86769 contains "a sample of patient's serum or plasma is diluted in buffer (...) the diluted sample and controls in duplicate are added to a multi-well plate, incubated and washed. Peroxidase-conjugates mouse anti-human IgG and IgM antibodies are added to the sample (...) A chromogenic substrate is added, incubated, and (...) read at 450nm using a microtiter plate reader. Results are interpreted and reported". This description outlines the multi-step process that is applicable, for example, when performing an ELISA.

#8 "CPT 86769 is applied for multi-step antibody tests (e.g. ELISA): Antibody; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]) (For severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] [Coronavirus disease {COVID-19}] antibody testing using single-step method, use 86328)"

Again, please note the CPT cross-reference to the single-step method.

The specific number of applied CPT codes is a combination of technique and reported isotypes. For example if a lateral flow assay can assess 2 isotypes simultaneoulsy, one 86328 is applied (i.e., one strip, one code). If on the other hand 2 separate lateral flow assays are assessing IgM and IgG, two 86328's are justified. Finally, in multi-step assays, each assessed and separately reported isotype gets one 86769 code. See cpt Assistant from April for details.

Towards Functional Serologic Assessments

The newest CPT code set is related to neutralization assays. Neutralization assays are complex (and if of not interest feel free to skip this section and jump to "Comprehensive Overview").

Neutralization tests. Virus neutralization assays are the gold standard in coronavirus serologic testing. Neutralizing antibodies are measured by plaque reduction neutralization test (PRNT). PRNT is a serological test which utilizes the ability of a specific antibody to neutralize a virus, in turn, preventing the virus from causing the formation of plaques in a culture dish (cell monolayer) during a plaque assay.

Specifically, during a plaque assay, a confluent monolayer cells is infected with a lytic virus. After the infection, the cellular monolayer is covered with an immobilizing medium to prevent lateral spread of the virus. Individual plaques (=zones of cell death in the monolayrer), will begin to develop as viral infection and replication are constrained to specific regions in the monolayer. Infected cells will continue the replication-lysis-infection cycle, further propagating the infection, resulting in increasingly distinct and discrete plaques.

In a SARS-CoV-2 neutralization assay, the virus solution is mixed with the blood (containing antibodies). If antibodies cover the virus, it cannot enter the cell and as a result the number of plaques is reduced or absent. The test thereby functionally measures whether an antibody can inhibit a SARS-CoV-2 infection, or, in other words, whether an antibody is actually protective.

#9 "CPT 86408 is used to code for screening by neutralization assays: Neutralizing antibody, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]); screen"

Neutralization assays can be applied to qualitatively "screen" whether antibodies are functionally neutralizing or not. The appropriate CPT code is 86408. In addition, one can apply the same assay using dilutions of the patients-derived antibodies to semiquantitatively assess the point of complete disappearance of plaque formation (i.e., determine the serologic titer).

#10 "When determining the titer in a neutralization assay, use CPT 86409: Neutralizing antibody, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]); titer"

Turn-around times are multiple days and PRNT requires a specialized facility (most settings won't have access to these technologies). For these reasons, most settings won't have access to these assays; however, surrogate techniques to assess neutralizing function have been developed (see PLA code 0226U in the table below).

A Comprehensive Overview

The above outline covers the 6 main CPT (Category I) codes implemented for COVID-19 diagnostics (status August 31 2020). For a more comprehensive overview, the following table contains:

• CPT codes and short descriptors
• the long (official) descriptors
• the AMA release date (for localization of the appropriate CPT assistant)
• all COVID-19 related PLA codes and the corresponding Company/Laboratory Information when applicable
• the specific short description name for the procedure in the clinical laboratory fee schedule (CLFS from CMS; status CLAB2020Q3) *note several codes are expected to be included in CALB2020Q4

Limitations

The outlined framework can only be a start. We are still learning how to most effectively apply and utilize these tests. Clinical indications continue to evolve alongside our knowledge of the complex immunobiology of COVID-19. The complexity of the coding framework for COVD-19 diagnostics is on the other hand manageable - at least when focusing on CPT codes.

Please keep in mind that there are many additional requirements to achieve successful billing practices. For example, federal or local determinants (e.g., executive orders), payor related aspects, policies that delineate the appropriate CPT codes and the specific clinical presentation (e.g., covered ICD-10 codes). The clinical utility of a given procedure might differ between patients or settings. Nontheless, PCR and serologic testing can complement each other. Thus, some patients require multiple test types (i.e., different CPT codes) and/or multiple tests (i.e., multiple identical CPT codes). It finally reamins to be determined whether newer COVID-19 diagnostics will travers the outlined biological groups and assay-specific subgroups. Such extensions across the frameowkr are for example, some sandwich and array technologies that combine antibody and PCR technologies. It remains to be determined how we code these compound diagnostics. Finally, the quality of the coding teams and their ability to quickly adopt new practices likely differs between settings.

Conclusion

Capturing COVID-19 diagnostic procedures via appropriate CPT codes is one critical aspect of correct billing practices. The presented framework can be understood as the current biological grouping with assay-/or technology-specific subgroupings. Many additional puzzle pieces remain; however, understanding the underlying logic of the CPT coding framework might be helpful to mentally integrate future updates and work towards achieving financial sustainability.

JL-8/31/2020