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Pathology/Lab Coding Alert

Serological Testing:

Update SARS-CoV-2 Code Options for Antibody Tests

Master CPT® April 10 revisions.

Whether your lab uses a laboratory-developed test or a commercial kit for SARS-CoV-2 serology testing, you can’t afford to miss FDA guidance and expedited CPT® coding options for these services.

Read on: We have the essential information you need to understand antibody testing, FDA policy, and AMA instruction involving the SARS-CoV-2 virus, which causes the disease, COVID-19.

Grasp Antibody Test Functions, Methods

You might see several terms used to describe tests that evaluate the body’s response to infection with SARS-CoV-2, including immunology, antibody testing, or serology (serological) testing. All these terms refer to tests to detect if a person’s immune system has developed antibodies against the virus.

“Serological tests measure the … antibodies or proteins present in the blood when the body is responding to a specific infection, like COVID-19. In other words, the test detects the body’s immune response to the infection caused by the virus rather than detecting the virus itself,” explained Stephen M. Hahn MD, FDA commissioner in an April 7 press release.

Advantages: Serology test results, along with clinical parameters, may allow physicians to determine if an individual has immunity to SARS-CoV-2, even if the patient did not have symptoms or a confirmed case of COVID-19. “In addition, these test results can aid in determining who may donate a part of their blood, called convalescent plasma, which may serve as a possible treatment for those who are seriously ill from COVID-19,” Hahn stated.

Finally, serological surveys that include antibody testing of many individuals may allow epidemiologists to determine the pattern and extent of viral spread in the population.

“Antibody testing that identifies patients that have been exposed to the novel coronavirus (SARS-CoV-2) and developed an immune response is likely to have important public health implications by providing a clearer picture of the prevalence of the disease in the U.S.,” said Patrice A. Harris, MD, MA, president of the AMA in an April 10 press release.

Limitations: Antibody tests aren’t useful to diagnose a current infection with SARS-CoV-2, because it takes the body time following active infection (early studies indicate about 10 days) to develop detectable serum levels of antibodies, such as immunoglobulin G (IgG). For the same reason, improper timing of serology tests may result in erroneous test results.

Also, interpreting antibody test results is not straightforward, requiring validation that uses accurate information about the level of COVID-19 infection in the population.

“When not properly evaluated, [antibody tests] have the potential to misdiagnose and misinform,” cautioned Christopher W. Farnsworth, MD, and Neil W. Anderson, MD, lab experts from the Washington University School of Medicine in St. Louis in an April 28 press release from the American Association for Clinical Chemistry (AACC).

Lab methods: With the advent of many SARS-CoV-2 antibody tests, labs may employ different methods to detect immunoglobulins indicating exposure to the virus. Labs may develop their own tests, many of which are multi-step immunoassays that use complex instrumentation and may provide qualitative or quantitative results.

On the other hand, some labs, notably point-of-care laboratories, may use commercial test kits. These tests include all the elements needed to perform a one-step, quick antibody test on a specimen such as blood from a finger stick, using a simple mechanism such as a reagent test strip. The results of these tests are typically qualitative or semiquantitative.

Follow FDA Direction

To facilitate early access to serological SARS-CoV-2 testing, the FDA issued guidance on March 16 to allow developers to market or use their tests without prior FDA review, subject to meeting certain conditions.

Specifically, the FDA policy states, “We recognize that serology tests are less complex than molecular tests and are solely used to identify antibodies, which limits their effectiveness for diagnosis; however … the FDA does not intend to object to the distribution and use of serology tests to identify antibodies to SARS-CoV-2 where the test has been validated, notification is provided to the FDA, and warning statements are included with the tests, for example, noting the test has not been reviewed by the FDA and results from antibody testing should not be used as the sole basis to diagnose or exclude SARS-CoV-2 infection or to inform infection status.”

In an April 7 statement, the FDA indicated that more than 70 test developers had notified the agency of serological tests available for lab use.

According to the statement, “The FDA can also authorize tests for COVID-19 under an Emergency Use Authorization (EUA),” and has authorized one serological test under the EUA, which is the qSARS-CoV-2 IgG/IgM Rapid Test by Cellex Inc. for the qualitative detection of IgM and IgG antibodies against SARS-CoV-2 in whole blood, serum, or plasma. Only labs certified under the Clinical Laboratory Improvement Amendments (CLIA) to perform moderate and high complexity tests are authorized to perform the test.

Conquer CPT® Changes

According to the CPT® Assistant Special Edition: April Update, “The CPT® Editorial Panel has revised one code and established two additional codes to provide increased specificity to report serologic laboratory testing.” The changes, effective April 10, came during a special meeting of the panel, convened “to address the urgent clinical need to report (and track) antibody testing.”

Two new codes: CPT® adds the following codes to the immunology section for SARS-CoV-2 antibody testing:

  • 86328 (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]))
  • 86769 (Antibody; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]))

The key distinction between the two codes is whether the test uses a multiple-step method (86769) or single-step method (86328), according to added CPT® text notes.

Code placement: CPT® places 86328 as a child code, resequenced and indented under 86318 (Immunoassay for infectious agent antibody(ies), qualitative or semiquantitative, single step method (eg, reagent strip);), which was revised to make it the parent code.

CPT® places 86769 as a child code under parent code 86710 (Antibody; influenza virus), although it appears in alphabetical order following 86768 (Antibody; Salmonella).

Notes: To accommodate the two new codes, CPT® revises the Immunology section introduction to include 86328 for single-step tests. You’ll also find a new note in alphabetical order for COVID-19 under 86635 (Antibody; Coccidioides) stating, “(For severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] [Coronavirus disease {COVID-19}] antibody testing, see 86328, 86769).”

Multiple antibody classes: If the lab tests for two antibody classes, such as IgG and IgM, you might be able to report two codes, depending on the circumstances, according to the CPT® Assistant Special Edition: April Update.

For instance: If a single lab test checks for two antibody classes, such as a reagent strip for IgG and IgM in a single test, you should report just one unit of 86328. On the other hand, if the lab performs two separate tests, whether two separate single-step assays or two separate multiple-step assays, you can report two units of 86328 or 86769, respectively. Depending on your payer, you may need to append a modifier such as 59 (Distinct procedural service) to the second test code.

Resources: You may access the relevant FDA files at www.fda.gov/news-events/fda-newsroom/press-announcements and the AMA coding guidance at www.ama-assn.org/practice-management/cpt/covid-19-coding-and-guidance.

Editor’s note: Information related to COVID-19 is changing rapidly. This information was accurate at the time of writing. Be sure to stay tuned to future issues of Pathology/Lab Coding Alert for more information. You can also refer to payer websites, CMS (cms.gov), CDC (cdc.gov), and AAPC’s blog (www.aapc.com/blog) for the most up-to-date information.