Coding long COVID: characterizing a new disease through an ICD-10 lens

Area of Science:

• Medical Informatics
• Public Health
• Epidemiology

Background:

• Naming new diseases like long COVID is challenging, especially with diagnostic codes lagging behind clinical descriptions.
• The ICD-10-CM code U09.9 for Post COVID-19 condition, unspecified, was deployed nearly two years after patient-reported symptoms emerged.
• Understanding the adoption and utilization patterns of this code is crucial for managing the long COVID pandemic.

Purpose of the Study:

• To examine the heterogeneity in the adoption and use of the ICD-10-CM code U09.9 for post-COVID-19 conditions.
• To analyze demographic factors, social determinants of health, and co-occurring conditions associated with U09.9 diagnoses.
• To identify patterns in medications and procedures for patients with U09.9 codes, stratified by age.

Main Methods:

• Utilized the largest publicly available HIPAA-limited dataset of COVID-19 patients in the US.
• Analyzed 33,782 patients with the U09.9 diagnosis code, assessing demographics and social determinants of health.
• Employed Louvain clustering for co-occurring diagnoses and quantified associated medications and procedures within 60 days of diagnosis.

Main Results:

• Co-occurring diagnoses with U09.9 were clustered into cardiopulmonary, neurological, gastrointestinal, and comorbid categories.
• Patients with U09.9 diagnoses were disproportionately female, White, non-Hispanic, and from areas with low poverty and unemployment.
• Characterized common medications and procedures linked to U09.9-coded patients, with age-stratified analysis.

Conclusions:

• The study provides insights into potential long COVID subtypes and current clinical practice patterns.
• Significant demographic skews in U09.9 diagnosis suggest potential disparities in long COVID diagnosis and care.
• Urgent research and remediation are required to address identified disparities in diagnosing patients with long COVID.