Characterization of Post-COVID-19 Definitions and Clinical Coding Practices: Longitudinal Study.

Area of Science:

• Medical Informatics
• Public Health
• Infectious Diseases

Background:

• Post-COVID-19 condition, or long COVID-19, lacks a universal clinical definition.
• Electronic health record (EHR) data are crucial for understanding long COVID-19.
• The ICD-10 code U09.9 for Post COVID-19 condition is used in EHRs, but its accuracy is uncertain.

Purpose of the Study:

• To assess the accuracy and utility of the ICD-10 code U09.9 for identifying long COVID-19.
• To compare the U09.9 code's performance against clinical case definitions across three major health care systems.
• To evaluate the code's effectiveness using operationalized World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) definitions.

Main Methods:

• Reviewed 900 patient charts across the Veterans Health Administration, Beth Israel Deaconess Medical Center, and University of Pittsburgh Medical Center.
• Identified patients with COVID-19 using ICD-10 code U07.1 or positive PCR tests.
• Sampled patients with and without the U09.9 code, applying a long COVID-19 definition based on symptom duration, onset, and core symptom clusters.

Main Results:

• The prevalence of long COVID-19 among patients with the U09.9 code ranged from 23.2% to 62.4% across the health care systems.
• Using less stringent WHO and CDC definitions increased the observed prevalence of long COVID-19 at all sites.
• The study provides initial insights into the performance of the U09.9 code in real-world EHR data.

Conclusions:

• This study is among the first to validate the U09.9 code against a clinical case definition for long COVID-19.
• The chart review approach, applied nationwide across multiple health systems, demonstrates the feasibility of evaluating EHR code accuracy.
• The findings suggest the U09.9 code's utility varies, highlighting the need for further evaluation in diverse EHR systems.