Validation of ICD-10-CM diagnosis codes for identifying COVID-19 cases using administrative claims data in Taiwan.

Publication date: May 23, 2026

Accurate identification of COVID-19 cases is essential for real-world studies. This study assessed the validity of ICD-10-CM code U07. 1 for identifying COVID-19 cases in administrative claims data in Taiwan. This observational validation study linked National Health Insurance claims with laboratory-confirmed SARS-CoV-2 RT-PCR results from a multi-institutional database. We included 127,300 outpatient, emergency, and inpatient encounters from 2022. Positive and negative predictive values (PPV, NPV), sensitivity, and specificity were calculated using RT-PCR results as the reference standard, with stratified analyses conducted by clinical setting, time period, patient demographics, and hospital level. Overall, the U07. 1 code demonstrated high PPV (95. 3%) and specificity (99. 5%), but moderate NPV (77. 9%) and low sensitivity (26. 6%). While PPVs remained consistently high across all clinical settings (> 91%), NPVs varied significantly, being lowest in outpatient visits (41. 3%). Temporally, NPV and sensitivity were lowest during April-June 2022 (57. 7% and 14. 9%, respectively), coinciding with the peak outbreak and the transition toward antigen-based diagnostic policies. Sensitivity was markedly higher among inpatients (84. 4%) and older adults aged ≥ 80 years (60. 5%) compared to younger populations. ICD-10-CM U07. 1 is a highly reliable marker for identifying confirmed COVID-19 cases in Taiwan’s claims data. However, the low overall sensitivity and substantial variability in NPV suggest significant under-capture of mild infections, particularly in outpatient settings. Researchers should exercise caution when using this code to estimate total disease burden or when defining code-negative control cohorts.

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