Validation Study of the Claims‐Based Algorithm Using the International Classification of Diseases Codes to Identify Patients With Coronavirus Disease in Japan From 2020 to 2022: The VENUS Study.

Purpose: We validated claims‐based algorithms using the International Classification of Diseases, Tenth Revision (ICD‐10) to identify patients with the first‐ever coronavirus disease (COVID‐19) onset between May 2020 and August 2022. Methods: The study cohort was comprised of residents of one municipality enrolled in a public insurance program. This study used data provided by the municipality, including residents' insurer‐based medical claims data linked to the Health Center Real‐time Information‐Sharing System (HER‐SYS). The HER‐SYS data included positive results from COVID‐19 tests and were used as reference standards. Claims‐based algorithms #1 and #2 were U07.1, B34.2, with and without suspicious diagnoses, respectively. Claims‐based algorithms #3 and #4 were U07.1 with and without suspicious diagnoses, respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each algorithm. Results: The study cohort included 165 038 residents, including 13 402 residents were the reference standard. For the entire period, the sensitivity, specificity, PPV, and NPV were 55.7% (95% confidence interval: 54.8%–56.5%), 65.4% (65.2%–65.6%), 11.5% (11.3%–11.8%), and 98.9% (98.8%–99.0%) for Algorithm #1, and 67.0% (66.2%–67.8%), 88.1% (87.9%–88.3%), 31.6% (31.1%–32.2%), and 97.8% (97.7%–97.8%) for Algorithm #2, and 52.9% (52.0%–53.7%), 67.1% (66.9%–67.3%), 11.5% (11.2%–11.8%), and 98.3% (98.3%–98.4%) for Algorithm #3, 62.6% (61.8%–63.4%), 88.5% (88.3%–88.7%), 30.9% (30.3%–31.4%), and 97.3% (97.2%–97.4%) for Algorithm #4, respectively. Conclusions: Our study showed that the validity of claims‐based algorithms consisting of COVID‐19‐related ICD‐10 codes to identify patients with first‐onset COVID‐19 is limited. [ABSTRACT FROM AUTHOR]