Coding Long COVID: Characterizing a new disease through an ICD-10 lens

Abstract

Naming a newly discovered disease is always challenging; in the context of the COVID-19 pandemic and the existence of post-acute sequelae of SARS-CoV-2 infection (PASC), which includes Long COVID, it has proven especially challenging. Disease definitions and assignment of a diagnosis code are often asynchronous and iterative. The clinical definition and our understanding of the underlying mechanisms of Long COVID are still in flux. The deployment of an ICD-10-CM code for Long COVID in the US took nearly two years after patients had begun to describe their condition. Here we leverage the largest publicly available HIPAA-limited dataset about patients with COVID-19 in the US to examine the heterogeneity of adoption and use of U09.9, the ICD-10-CM code for “Post COVID-19 condition, unspecified.”Our results include a characterization of common diagnostics, treatment-oriented procedures, and medications associated with U09.9-coded patients, which give us insight into current practice patterns around Long COVID. We also established the diagnoses most commonly co-occurring with U09.9, and algorithmically clustered them into three major categories: cardiopulmonary, neurological, and metabolic. We aim to apply the patterns gleaned from this analysis to flag probable Long COVID cases occurring prior to the existence of U09.9, thus establishing a mechanism to ensure patients with earlier cases of Long-COVID are no less ascertainable for current and future research and treatment opportunities.

Long COVID Symptomatology After 12 Months and Its Impact on Quality of Life According to Initial Coronavirus Disease 2019 Disease Severity

“…In less frequently reported symptoms, we have seen that gastrointestinal symptoms (nausea, diarrhea, stomach burn, and other abdominal pain) on one hand and loss of taste and loss of smell on the other hand usually co-occurred. This is consistent with findings from other studies confirming that different clusters of long COVID can be described and could benefit from adapted treatments and diagnosis [ 37 , 42 ].…”

Risk Factors Associated with Post-Acute Sequelae of SARS-CoV-2 in an EHR Cohort: A National COVID Cohort Collaborative (N3C) Analysis as part of the NIH RECOVER program

“…An index date was required to determine the relative timing of infection and long-COVID diagnosis (International Classification of Diseases, Tenth Revision, Clinical Modification [ICD-10-CM] code U09.9) or long-COVID clinic visit. Not all health systems currently use U09.9 or have clinics dedicated to long-COVID treatment [22]. Therefore, we limited our cohort to patients from the 31 health systems with at least one documented long-COVID case using U09.9 or a long-COVID clinic visit between Oct 1, 2021 and Feb 28, 2022 (n=1,490,823).…”

SARS-CoV-2 Reinfection is Preceded by Unique Biomarkers and Related to Initial Infection Timing and Severity: an N3C RECOVER EHR-Based Cohort Study

“…Many hospital sites appear to have rapidly adopted the use of U09.9 once it became available. 28 The B94.8 code is not specific to COVID-19 and instead represents sequelae of other specified infectious and parasitic diseases. This code was rarely used prior to the pandemic, but it started seeing considerably more use in November 2020.…”

“…The use of this code is understood to represent Long COVID diagnoses prior to the availability of U09.9. 28 For the purposes of the Long COVID analysis, we limited the study cohort to individuals at sites that had at least 250 uses of either the U09.9 code after October 1, 2021 or the B94.8 code after November 1, 2020. Eligible reinfections for U09.9 or B94.8 had to occur after the respective dates of use of the codes.…”