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EDITOR’S NOTE: Dr. Remer reported on this topic during today’s edition of Talk Ten Tuesdays.

We are getting more sophisticated and knowledgeable about COVID-19, but I am still getting a lot of questions. Many of them are variations on the theme of what to do with patients who are being tested for COVID-19, had it previously, or currently test positive for antibodies for COVID-19, suggesting a previous infection.

Examples are:

  • We had a patient come to the ED and had antibody testing done, yielding a positive result. COVID-19 testing was then done, which was negative. The ED physician suspected that the patient had COVID-19 previously, but it had resolved. Would history of COVID-19 be the code to use, along with Z20.828, since testing was done?
  • A patient was admitted and diagnosed with COVID-19. A few weeks later, they return, and the provider tests the patient again with a PCR test, which returns positive. The provider documents “likely dead or persistent virus particles.” American Hospital Association (AHA) FAQs advise us to capture U07.1, COVID-19, for a positive test. Is this really U07.1, or history of, Z86.19?
  • I’m still not clear what to use for preoperative COVID-19 testing, Z11.59 or Z20.828.

Of course, your coding is going to be predicated on the provider’s documentation, but here are my suggestions. The clinical information derives from the Centers for Disease Control and Prevention (CDC) website: https://www.cdc.gov/coronavirus/2019-ncov/hcp/faq.html.

There are two types of tests associated with COVID-19, diagnostic tests and antibody tests. Cultures are not done for SARS-CoV-2, the virus that causes the disease COVID-19. There are two types of diagnostic tests:

  • Molecular tests, such as the reverse transcriptase polymerase chain reaction test (RT-PCR, or PCR for short), which detect genetic material from the virus; and
  • Antigen tests, which are usually more rapid and pick up specific proteins found on the surface of the virus. Antigen tests are often referred to as “screening” (not in the Z11.59 sense of the word) and are followed up with confirmatory PCR testing (see Ohio Governor Mike DeWine’s false positive fiasco from Aug. 6: https://www.cnn.com/2020/08/09/politics/mike-dewine-coronavirus-test-cnntv/index.html).

Antibody or serological tests are looking for an immune reaction response to a COVID-19 infection, which usually take days to weeks to develop. They are not intended to be used as tools to diagnose acute infection.

PCR tests can be positive from a current infection, still within the period of infectiousness, or can be positive from persistent viral RNA when the patient is no longer infectious. Most recovered patients do not have detectable SARS-CoV-2 RNA, and if they do, it has not been found to be associated with the ability to replicate and infect others, especially after 2-3 weeks post-illness. Sometimes, a follow-up positive test after a negative PCR is related to the second test being a different brand, with the ability to detect lower amounts of viral RNA. The CDC says that there is “no evidence to date that clinically recovered persons with persistent or recurrent detection of viral RNA have transmitted SARS-CoV-2 to others.”

The CDC does not recommend re-testing to demonstrate that patients are no longer infectious. For immunocompetent patients with mild to moderate COVID-19, replication-competent virus has not been recovered after 10 days following symptom onset. See the CDC website for the recommended symptom-based strategy: (https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html).

The code of U07.1 is intended to signify a current COVID-19 infection. Infections can be symptomatic, with a wide variety of signs and symptoms, or they can be asymptomatic. Z86.19 is Personal history of other infectious and parasitic diseases, and B94.8 is Sequelae of other specified infectious and parasitic diseases.

If the provider diagnoses the patient with what is felt to be a current infection, symptomatic or not, the code is U07.1. If a patient is symptomatic and being worked up for a current infection, a positive test is permitted to be inferred by the coder to indicate U07.1.

If a patient has a positive antibody test, and the provider suspects and documents that there was a prior COVID-19 infection, then Z86.19 is appropriate. If there is some medium- or long-term sequela from the infection (e.g., myocarditis, pulmonary fibrosis), then the code to use is B94.8 instead (along with the code for the manifestation of the sequela). Z20.828 would not be appropriate for these patients; it is not a question of exposure, it is a matter of having a prior infection, i.e., U07.1, at the time.

The use of Z01.84 denotes encounter for antibody response examination, but it must be first-listed and would be an absurd principal diagnosis. If the antibody test is positive, R76.8, Other specified abnormal immunological findings in serum, could signify the abnormal (albeit desirable) serological response.

If there is a continued or recurrent positive PCR test, the coder must ferret out whether the provider thinks the patient has a current infection (U07.1), or whether they think it is from a previous, resolved infection (Z86.19 or B94.8, depending on the circumstances). It is not best-practice medicine to use an antibody test to guide the obtaining of a PCR test. Even though AHA gives the coder permission to code the positive PCR test as U07.1, the coder needs to determine if that is a clinically valid scenario. If the provider documents “probably represents dead or persistent virus particles,” they are signaling that they believe it to be a prior infection. In this case, use Z86.19 instead of U07.1.

AHA has been giving us excellent guidance with their FAQs, which are being regularly updated and posted: https://www.codingclinicadvisor.com/sites/default/files/Frequently%20Asked%20Questions%20Regarding%20COVID-19_v12.pdf. Question 38, from the Aug. 5 update, indicates that for preoperative testing during the pandemic (outpatient encounter, I presume), you should be utilizing Z01.812, Encounter for preprocedural laboratory examination, as the first-listed diagnosis, and Z20.828 as an additional diagnosis (unless the test is positive, which would be coded as U07.1).

Finally, those of you who are loyal Talk Ten Tuesdays listeners know my eyes glaze over when we talk about money, but this issue seems important to address. I saw a question on an American Health Information Management Association (AHIMA) discussion chat asking what diagnosis to use for COVID-19 testing without a doctor’s order, for folks who perform self-referral on those long lines we see on the news. They also asked how one bills if there is no physician order.

The reason for the encounter in this case is Z20.828. Specifically regarding Medicare patients, during the public health emergency (PHE), the Centers for Medicare & Medicaid Services (CMS) has removed the requirement that the clinical diagnostic laboratory tests for COVID-19  and related influenza or RSV be ordered by a treating physician or NPP: (https://www.cms.gov/files/document/03092020-covid-19-faqs-508.pdf).

Please check out our electronic COVID-19 Coding Flowcharts, available for purchase at ICDUniversity  (https://shop.icd10monitor.com/covid-19-icd-10-cm-coding-flowcharts-p/iecov20.htm) for more help on properly coding all these scenarios. We revise them as the coding evolves.

Programming Note: Dr. Remer co-hosts Talk Ten Tuesdays with Chuck Buck every Tuesday at 10 a.m. EST.


Erica E. Remer, MD, CCDS

Erica Remer, MD, FACEP, CCDS, has a unique perspective as a practicing emergency physician for 25 years, with extensive coding, CDI, and ICD-10 expertise. As physician advisor for University Hospitals Health System in Cleveland, Ohio for four years, she trained 2,700 providers in ICD-10, closed hundreds of queries, fought numerous DRG clinical determination and medical necessity denials, and educated CDI specialists and healthcare providers with engaging, case-based presentations. She transitioned to independent consulting in July 2016. Dr. Remer is a member of the ICD10monitor editorial board and is the co-host on the popular Talk Ten Tuesdays weekly, live Internet radio broadcasts.

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