Identifying COVID-19 Disease Severity in Real-World Data: Implications for Medical Product Effectiveness Studies

The U.S. Food and Drug Administration (FDA) defined disease severity criteria to assist clinical development of medical products for management of COVID-19. These definitions were translated to code-based algorithms for use in real-world data. We validated the algorithms' performance in ambulatory settings at three regional integrated healthcare delivery systems contributing data to FDA's Sentinel System.

We identified cohorts of individuals ≥ 18 years that met the algorithms' criteria for mild, moderate, and severe COVID-19 at incident COVID-19 diagnosis or positive SARS-CoV-2 test, and separately, at incident COVID-19 treatment, from January 2022 through April 2023. We validated the algorithms via chart review of a random sample to calculate positive predictive values (PPVs) and 95% CIs.