Clinical Epidemiology of Hospitalized Patients with Coronavirus Disease 2019 (COVID-19) in Japan: Report of the COVID-19 Registry Japan

Nobuaki Matsunaga, Kayoko Hayakawa, Mari Terada, Hiroshi Ohtsu, Yusuke Asai, Shinya Tsuzuki, Setsuko Suzuki, Ako Toyoda, Kumiko Suzuki, Mio Endo, Naoki Fujii, Michiyo Suzuki, Sho Saito, Yukari Uemura, Taro Shibata, Masashi Kondo, Kazuo Izumi, Junko Terada-Hirashima, Ayako Mikami, Wataru SugiuraNorio Ohmagari

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109 Citations (Scopus)


Background: There is limited understanding of the characteristics of patients with coronavirus disease 2019 (COVID-19) requiring hospitalization in Japan. Methods: This study included 2638 cases enrolled from 227 healthcare facilities that participated in the COVID-19 Registry Japan (COVIREGI-JP). The inclusion criteria for enrollment of a case in COVIREGI-JP are both (1) a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test and (2) inpatient treatment at a healthcare facility. Results: The median age of hospitalized patients with COVID-19 was 56 years (interquartile range [IQR], 40-71 years). More than half of cases were male (58.9%, 1542/2619). Nearly 60% of the cases had close contact to confirmed or suspected cases of COVID-19. The median duration of symptoms before admission was 7 days (IQR, 4-10 days). The most common comorbidities were hypertension (15%, 396/2638) and diabetes without complications (14.2%, 374/2638). The number of nonsevere cases (68.2%, n=1798) was twice the number of severe cases (31.8%, n=840) at admission. The respiratory support during hospitalization includes those who received no oxygen support (61.6%, 1623/2636) followed by those who received supplemental oxygen (29.9%, 788/2636) and invasive mechanical ventilation/extracorporeal membrane oxygenation (8.5%, 225/2636). Overall, 66.9% (1762/2634) of patients were discharged home, while 7.5% (197/2634) died. Conclusions: We identified the clinical epidemiological features of COVID-19 in hospitalized patients in Japan. When compared with existing inpatient studies in other countries, these results demonstrated fewer comorbidities and a trend towards lower mortality.

Original languageEnglish
Pages (from-to)E3677-E3689
JournalClinical Infectious Diseases
Issue number11
Publication statusPublished - 01-12-2021

All Science Journal Classification (ASJC) codes

  • Microbiology (medical)
  • Infectious Diseases


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