One Code Alone is Inadequate to tell the COVID-19 Sequela Story

Original story posted on: December 21, 2020

I am imploring the official powers that be to reconsider the advice and permit us, instruct us, to use Z86.16 with B94.8.

When I am doing webinars, I preface them with the disclaimer that I am not a coder; I only play one on the computer. However, there are times when there are what I affectionately refer to as coding-clinical disconnects, wherein I have to respectfully disagree with the coding community, according to my clinical judgment.

We have been using a generic sequela code for residual effects of COVID-19, B94.8, Sequelae of other specified infectious and parasitic diseases. As a clinician or statistician, if I see this code, my inquiring mind wants to know what the sequela is, and from what. Until Jan. 1, 2021, the only personal history code we have to indicate a history of COVID-19 is Z86.19, Personal history of other infectious and parasitic diseases. Using these two codes together is redundant, and adds no actionable information. However, as of Jan. 1, we will have a specific code for COVID-19 history, Z86.16. It is my educated opinion that the use of B94.8 with Z86.16 gives very critical information, and so I recommend using them in tandem.

Personal communication from the American Hospital Association (AHA) notes that their position is that it is incorrect to use these codes together, as they have different meanings. “A sequela is the residual effect (condition produced) after the acute phase of an illness or injury has terminated,”. “There is no time limit on when a sequela code can be used.”

They further informed me that, in contradistinction, “personal history codes explain a patient’s past medical condition that no longer exists and is not receiving any treatment, but that has the potential for recurrence, and therefore may require continued monitoring.” I respectfully disagree. I assert that personal history (PH) codes indicate an illness or injury that has resolved, but which may have significant implications to the patient’s current or future medical condition.

Many of these conditions (which have dedicated PH codes) do have the potential for recurrence, such as PH of urinary tract infections, methicillin-resistant Staphylococcus aureus infection, or pulmonary embolism. Some require continued monitoring, such as PH of (benign) colonic polyps or malignant neoplasms. But many personal history codes just inform the provider and afford context for clinical decisions. Examples of these would be PH of (corrected) congenital malformations or PH of sex reassignment. There is no potential for recurrence, and continued monitoring is not indicated. It is just detail of personal history. It is an applicable secondary diagnosis if it is clinically relevant to the current situation.

A patient with a contracture impairing the function of their right hand from a previous serious burn, presenting to a plastic surgeon for repair, would be coded with L90.5, Scar conditions and fibrosis of skin and  T23.331S, Burn of third degree of multiple right fingers (nail), not including thumb, sequela. That combination of codes gives us all relevant information: that there is a sequela (seventh character S), what the sequela is (L90.5), the site affected by the sequela (multiple right fingers), and what caused the sequela (a burn). The burn is resolved, but it has left a complication in its wake. The burn is historical. The sequela, its consequence, is current.

If a personal history code is only for “a past medical condition that no longer exists and is no longer receiving treatment, but there is potential for recurrence, and, therefore, may require continued monitoring,” then Z86.16 was unnecessary. Once COVID-19 has resolved, there has not been evidence of recurrence (despite the fact that there can be prolonged viral shedding/remnants in some cases). That is not why this code was created; it was created so we could surveil past prevalence and get a handle on case rates. We want to know what percentage of the population has had the disease already.

Z86.19 is a code that you could use for personal history of varicella zoster, mumps, measles, Ebola, hepatitis, human papilloma, Lyme disease, syphilis, etc. Correspondingly, if a patient were to have testicular atrophy from mumps or Bell’s palsy from Lyme disease, you would use B94.8 to notate that. As a result, B94.8 is very nonspecific, and can’t really be used as a proxy indicator for a sequela of COVID-19. In other words, if an epidemiologist wanted to parse out how many patients were experiencing sequelae from COVID-19, like cardiomyopathy, pulmonary fibrosis, or post-viral fatigue syndrome, they couldn’t do so, because the data would be polluted with sequelae from myriad infectious and parasitic diseases occurring in the same time span.

However, if they looked for encounters that had B94.8 plus Z86.16 coded, they could identify sequelae that had resulted from COVID-19. This wouldn’t be foolproof; if a patient had a history of COVID-19 three weeks ago, but the B94.8 was indicating complete heart block from Lyme disease, it might confound the picture, but one would expect this to be a rare occurrence. There is no “personal history of Lyme disease” code to signify the association. It would also only be relevant from Jan. 1, 2021 forward.

AHA/AHIMA (American Health Information Management Association) has FAQs regarding ICD-10 COVID-19 coding. FAQ No. 28 asks about coding a pneumothorax resulting from a previous COVID-19 infection, and the response was to use J93.83, Other pneumothorax as PDx, followed by B94.8. The final sentence reads “the patient is clearly receiving treatment for the residual effect of COVID-19.” As a clinician, I disagree. The patient is receiving treatment for a pneumothorax (chest tube), which would be the same treatment if it were from a COPD bleb or a traumatic injury. The pneumothorax happens, in this case, to be from COVID-19. The patient is not receiving any treatment aimed at COVID-19. Receiving treatment for a condition that has resulted from another disease process is not equivalent to receiving treatment for the causative disease.

The guidelines prohibit concurrent use of the code for the acute phase of an illness or injury that led to the sequela, but there is no explicit exclusion against concomitant use of a “personal history of” code ( The tabular index also instructs us to “use sequelae codes when the disease itself is no longer present.” It further instructs us that “chronic current infections would be coded as active infectious disease, as appropriate.”

There have been numerous reports of a post-COVID-19 syndrome referred to as long-haul COVID-19. It is not from persistent infection; it is a sequela of resolved acute infection. Without a mechanism to identify these cases, we will not be able to study, analyze, and combat it.

I am imploring the official powers that be to reconsider the advice and permit us, instruct us, to use Z86.16 with B94.8. The sequence would be sequela manifestation, followed by B94.8, informing us that the condition is a sequela of an infectious or parasitic disease, and then Z86.16, which would specify that the disease was COVID-19. This will give us all the information we need.

As I always say, use as many codes as it takes to tell the story.

Programming Note: Dr. Erica Remer is the co-host of Talk Ten Tuesdays. Listen to her every Tuesday when the live broadcast resumes on Jan. 12, 2021, 10 a.m. EDT.

Erica E. Remer, MD, FACEP, 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. She was a physician advisor of a large multi-hospital system for four years before transitioning to independent consulting in July 2016. Her passion is educating CDI specialists, coders, and healthcare providers with engaging, case-based presentations on documentation, CDI, and denials management topics. She has written numerous articles and serves as the co-host of Talk Ten Tuesdays, a weekly national podcast. Dr. Remer is a member of the ICD10monitor editorial board, the ACDIS Advisory Board, and the board of directors of the American College of Physician Advisors.

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