Association of Smoking and Severity of COVID-19 Infection Among 5,889 Patients in Malaysia: A Multi-Center Observational Study

Objective This study aims to investigate the association between smoking and the severity of COVID-19 infection during the initial wave of this pandemic in Malaysia.

Methods This is a multi-centre observational study using secondary hospital data collected retrospectively from 1^st February 2020 until 30^th May 2020. Clinical records of all real-time polymerase chain reaction (RT-PCR) confirmed COVID-19 cases with smoking status, co-morbidities, clinical features and disease management were retrieved. Severity was assessed by presence of complications and outcomes of COVID-19 infection. Logistic regression was used to determine the association between COVID-19 disease severity and smoking status.

Results A total of 5889 COVID-19 cases were included in the analysis. Ever smokers had higher risk of having COVID-19 complications such as acute respiratory distress syndrome (OR: 1.69, 95% CI = 1.09 - 2.55), renal injury (OR: 1.55, 95% CI = 1.10 - 2.14) and acute liver injury (OR: 1.33, 95% CI = 1.01 - 1.74) compared to never smokers. However, in term of disease outcomes, there were no differences between two groups.

Conclusion Although no significant association was found in term of disease outcomes, smoking is associated with higher risk of having complications due to COVID-19 infection.