Conventional and Kampo Medicine Treatment for Mild-to-moderate COVID-19: A Multicenter, Retrospective, Observational Study by the Integrative Management in Japan for Epidemic Disease (IMJEDI Study-observation)

OBJECTIVE: Patients in whom coronavirus disease 2019 (COVID-19) was suspected or confirmed between January 1, 2020, and October 31, 2021, were enrolled from Japanese hospitals in this multicenter, retrospective, observational study. METHODS: Data on the treatment administered (including conventional and Kampo medicine) and changes in common cold-like symptoms (such as fever, cough, sputum, dyspnea, fatigue, and diarrhea) were collected from their medical records. The primary outcome was the number of days without a fever (with a body temperature ＜37°C). The secondary outcomes were symptomatic relief and the worsening of illness, defined as the presence of a condition requiring oxygen inhalation. The outcomes of patients treated with and without Kampo medicine were compared. PATIENTS: We enrolled 962 patients, among whom 528 received conventional and Kampo treatment (Kampo group) and 434 received conventional treatment (non-Kampo group). RESULTS: Overall, after adjusting for the staging of COVID-19 and risk factors, there were no significant between-group differences in the symptoms or number of days being afebrile. After performing propensity score matching and restricting the included cases to those with confirmed COVID-19 who did not receive steroid administration and initiated treatment within 4 days from the onset, the risk of illness worsening was significantly lower in the Kampo group than in the non-Kampo group (odds ratio=0.113, 95% confidence interval: 0.014-0.928, p=0.0424). CONCLUSION: Early Kampo treatment may suppress illness worsening risk in COVID-19 cases without steroid use. Further randomized controlled studies are needed to confirm the clinical benefit of Kampo medicine for COVID-19.