Abstract
BACKGROUND: Coronavirus disease (COVID-19) is overwhelming healthcare systems worldwide. This study aimed to elucidate factors that influence disease progression to pneumonia and hospitalization before and after antiviral treatment for COVID-19 in an outpatient setting. METHODS: A total of 206 high-risk patients with COVID-19 were treated with sotrovimab, remdesivir, and molnupiravir at the Toshiwakai clinic between January 4 and April 30, 2022. Of these, 49 patients visited the Toshiwakai clinic directly and were treated immediately after diagnosis (Toshiwakai-clinic study group). The remaining patients were diagnosed elsewhere, and of these, 102 patients were quarantined at home (health-center study group) and 55 at designated facilities (quarantine-facility study group) before being referred to Toshiwakai clinic. Patients were categorized into those with mild and moderate COVID-19, based on the presence of pneumonia at the initial visit to Toshiwakai clinic. RESULTS: The symptom-onset-to-diagnosis and diagnosis-to-treatment intervals were significant predictors of moderate disease. Age, dyspnea, and diagnosis-to-treatment interval at the first visit to Toshiwakai clinic were significant predictors for hospitalization even after antiviral treatment. Although the symptom-onset-to-diagnosis interval did not differ among the three study groups, the diagnosis-to-treatment and symptom-onset-to-treatment intervals were significantly longer in the health-center and quarantine-facility study groups than in the Toshiwakai-clinic study group. CONCLUSION: The symptom-onset-to-diagnosis and diagnosis-to-treatment intervals reflect diagnostic and interventional delays, respectively, which are closely related to the current COVID-19 clinical management protocol. Easy access to the clinics and immediate antiviral treatment after diagnosis may be the best methods to prevent disease progression and hospitalization in high-risk patients.