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Smoking, Comorbidities, and Severity of Disease in Hospitalized COVID-19 Patients in Japan

23 Pages Posted: 25 May 2021

See all articles by Yumi Matsushita

Yumi Matsushita

National Center for Global Health and Medicine - Department of Clinical Research

Tetsuji Yokoyama

National Institute of Public Health - Department of Health Promotion

Kayoko Hayakawa

National Center for Global Health and Medicine - Disease Control and Prevention Center

Nobuaki Matsunaga

National Center for Global Health and Medicine - AMR Clinical Reference Center

Hiroshi Ohtsu

Juntendo University

Sho Saito

National Center for Global Health and Medicine - Disease Control and Prevention Center

Mari Terada

National Center for Global Health and Medicine - Disease Control and Prevention Center

Setsuko Suzuki

National Center for Global Health and Medicine - Disease Control and Prevention Center

Shinichiro Morioka

National Center for Global Health and Medicine - Disease Control and Prevention Center

Satoshi Kutsuna

National Center for Global Health and Medicine - Disease Control and Prevention Center

Tetsuya Mizoue

National Center for Global Health and Medicine - Department of Epidemiology and Prevention

Hisao Hara

National Center for Global Health and Medicine - Department of Cardiology

Akio Kimura

National Center for Global Health and Medicine - Department of Emergency Medicine and Critical Care

Norio Ohmagari

National Center for Global Health and Medicine - Disease Control and Prevention Center

More...

Abstract

Background: The aim of this study was to identify associations between smoking status and the severity of COVID-19 using a large-scale data registry of hospitalized COVID-19 patients in Japan (COVIREGI-JP) and to explore the reasons for the inconsistent results previously reported on this subject.

Methods: The analysis included 17,702 COVID-19 inpatients aged 20-89 years (10,279 men and 7,423 women). We graded the severity of COVID-19 (grade 0 to 5) according to the most intensive treatment required during hospitalization. Associations of smoking status with severe grade 3/4/5 (invasive mechanical ventilation/extracorporeal membrane oxygenation/death) and separately with grade 5 (death) were analyzed using multiple logistic regression with grade 0 (no oxygen) as the control group. Results were expressed as odds ratios (OR) and 95% confidence intervals (CI) adjusted for age and other factors considering the potential intermediate effects of comorbidities.

Findings: Among men, former smoking significantly increased the risk of grade 3/4/5 and grade 5, with age-adjusted ORs (95% CI) of 1·50 (1·18-1·90) and 1·65 (1·23-2·21), respectively. An additional adjustment for comorbidities weakened these ORs to 1·29 (1·00-1·66) and 1.41 (1·01-1·95), respectively. Similar results were seen for women. Current smoking did not significantly increase the risk of grade 3/4/5 and grade 5 in either sex.

Interpretation: Smoking cessation should be recommended even if the observed relationship between current smoking and the severity of COVID-19 is null because current smoking increases the risks of future comorbidities due to different diseases that increase the risk of severe COVID-19.

Funding Information: This research was funded by the Health and Labour Sciences Research grant (19HA1003, 20CA2031) and the National Center for Global Health and Medicine (20A-3002).

Declaration of Interests: All authors report no conflict of interest.

Ethics Approval Statement: This study was approved by the National Center for Global Health and Medicine (NCGM) ethics review (NCGM-G-003494-0).

Suggested Citation

Matsushita, Yumi and Yokoyama, Tetsuji and Hayakawa, Kayoko and Matsunaga, Nobuaki and Ohtsu, Hiroshi and Saito, Sho and Terada, Mari and Suzuki, Setsuko and Morioka, Shinichiro and Kutsuna, Satoshi and Mizoue, Tetsuya and Hara, Hisao and Kimura, Akio and Ohmagari, Norio, Smoking, Comorbidities, and Severity of Disease in Hospitalized COVID-19 Patients in Japan. Available at SSRN: https://ssrn.com/abstract=3845982 or http://dx.doi.org/10.2139/ssrn.3845982

Yumi Matsushita (Contact Author)

National Center for Global Health and Medicine - Department of Clinical Research ( email )

Tokyo
Japan

Tetsuji Yokoyama

National Institute of Public Health - Department of Health Promotion ( email )

Kayoko Hayakawa

National Center for Global Health and Medicine - Disease Control and Prevention Center

Tokyo
Japan

Nobuaki Matsunaga

National Center for Global Health and Medicine - AMR Clinical Reference Center ( email )

Tokyo 162-8655
Japan

Hiroshi Ohtsu

Juntendo University ( email )

2 Chome-1-1 Hongo
Tokyo
Japan

Sho Saito

National Center for Global Health and Medicine - Disease Control and Prevention Center

Tokyo
Japan

Mari Terada

National Center for Global Health and Medicine - Disease Control and Prevention Center ( email )

Tokyo
Japan

Setsuko Suzuki

National Center for Global Health and Medicine - Disease Control and Prevention Center ( email )

Tokyo
Japan

Shinichiro Morioka

National Center for Global Health and Medicine - Disease Control and Prevention Center ( email )

Tokyo
Japan

Satoshi Kutsuna

National Center for Global Health and Medicine - Disease Control and Prevention Center

Tokyo
Japan

Tetsuya Mizoue

National Center for Global Health and Medicine - Department of Epidemiology and Prevention ( email )

Tokyo 162-8655
Japan

Hisao Hara

National Center for Global Health and Medicine - Department of Cardiology ( email )

Tokyo 162-8655
Japan

Akio Kimura

National Center for Global Health and Medicine - Department of Emergency Medicine and Critical Care ( email )

Tokyo
Japan

Norio Ohmagari

National Center for Global Health and Medicine - Disease Control and Prevention Center

Tokyo
Japan

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