Use of the New ICD-10-CM Diagnosis Code for Post COVID-19 Condition in Routine Clinical Practice in the United States

Background: Post-acute sequelae are increasingly documented in patients recovering from coronavirus disease 2019 (COVID-19). A new International Classification of Diseases, Tenth Revision (ICD-10-CM) diagnosis code (U09.9 Post-COVID-19 condition, unspecified) was introduced by the Centers for Disease Control and Prevention on October 1, 2021.

Objectives: To examine the uptake of the new diagnosis code and describe concurrently diagnosed conditions to understand how the code is being used in routine clinical practice.

Methods: We identified patients with an ICD-10-CM code for post COVID-10 condition between October 1, 2021 and January 31, 2022 from de-identified claims in HealthVerity’s Real-Time Insights and Evidence database. The index date was the first post COVID-19 diagnosis date. To identify a prior COVID diagnosis, we required 3-months of continuous enrollment (CE) before the post COVID-19 diagnosis date. Demographic and clinical variables were summarized with descriptive statistics. The frequency of concurrent diagnosis codes was evaluated on the index date. We also assessed the most common diagnoses codes within the 30 days prior to the index post COVID-19 condition code.

Results: There were 56,143 patients with a post COVID-19 diagnosis code, with cases increasing in mid-December following the trajectory of the omicron case wave by 3-4 weeks. The analysis cohort included 12,622 subjects that remained after the 3-month pre-index CE criteria was applied. Among this cohort, the median age was 49 years, however, 8.6% were pediatric patients. The post COVID-19 code was more common among females (61%) and was used most often in the outpatient setting, although 14% of older adults were inpatient. Only 70.4% had a documented COVID diagnosis code (53% among children) and the median time between the COVID and post-COVID diagnosis code was 56 days. The most common concurrently coded conditions varied by age – children commonly experienced COVID-like symptoms (e.g., cough, breathing abnormalities), while respiratory failure and pneumonia were more common among adults >=65 years.

Conclusions: The post COVID-19 ICD-10-CM diagnosis code is being used to identify patients with continuing illness following the acute phase of disease in patients of all ages in the United States. The use of the post COVID-19 code encompasses a wide range of conditions. Widespread use of this code for research is limited until a standard definition of post COVID-19 is agreed upon by the medical and public health community. It will be important to monitor how the use of this code changes as the pandemic continues to evolve.