Effects of Smoking on COVID-19 Management and Mortality: An Umbrella Review

Table 3

Description of the findings reported in the eligible studies.

First author (reference)	Effect of smoking on COVID-19							Other findings
	Disease progression	Disease severity	Outcome	Hospital admission	Increase hospitalization	ICU admission	Mechanical ventilation
Alghamdi, S.A. [29]	More in smokers	More in smokers	Increased mortality and worse overall outcome in smokers	More admission in smokers	N/A	Increased in smokers	More in smokers	Smokers are more prone to have a severe disease and increased mortality rate
Baker, J [30]	More in tobacco users	More in tobacco users	-Increased mortality in tobacco users (17 studies); -Decreased mortality (1 study); No association between mortality and tobacco use (14 studies)	Higher admission rate in tobacco use	Longer hospital stay in tobacco users	Higher in tobacco users	Increased risk in tobacco use	Adverse outcome and higher mortality rate and more severe disease found in tobacco users
Farsalinos, K [31]	N/A	N/A	Worse outcome in current smoker, but still less than former smokers	Interesting finding of lower admission rate between smokers	N/A	N/A	N/A	More negative outcome among current smoker but les probability of hospital admission; But overall, smoking in not protective against COVID infection
Gonzalez-Rubio, J [32]	N/A	N/A	N/A	Lower in smokers	N/A	N/A	N/A	Lower hospital admission in smokers
Grundy, E. J [33]	Higher risk of progression in smokers	Sever disease in smokers	Adverse outcome in smokers	More in smokers	N/A	N/A	N/A	Smokers have greater risk of severe disease
Gulsen, A [34]	N/A	Sever disease in smokers	Increased mortality in smokers	N/A	N/A	Higher risk of ICU admission	N/A	Risk of severe COVID is increased with both current smoking and previous history of smoking
Hou, H [35]	N/A	N/A	Mortality is significantly higher in former smokers compared to current smokers	N/A	N/A	N/A	N/A	Significant increase in mortality rate in smokers(especially in former smokers compared to current smokers)
Kang, S [36]	Increase rate of disease progression	Smoking increase disease severity	Smoking increase mortality	N/A	Smoking increases hospitalized	N/A	N/A	N/A
Karanasos, A [27]	N/A	Increased severity	Increased mortality	N/A	Smoking increases the risk of hospitalized	N/A	N/A	Association of smoking with severity was not significant (10 studies with 4152 patients)
Kumar, R [37]	N/A	Significant association with severity	N/A	N/A	N/A	N/A	N/A
Li, J [38]	N/A	Significantly associated with severe COVID-19	N/A	N/A	N/A	Significantly associated with severe (ICU) COVID-19	N/A
Luo, S [39]	N/A	Strong associations with smoking	Strong associations with smoking	N/A	Strong associations with smoking	N/A	N/A
Mahamat-Saleh, Y [40]	N/A	N/A	Increased absolute risk of death	The absolute risk of COVID-19 death increased by 7%	N/A	N/A	N/A	In this study show risk of death increase in ever smoker 28% current 29% and former 25%
Mattey-Mora, PP [41]	N/A	N/A	N/A	N/A	Smoking increases hospitalized	N/A	N/A
Mesas, AE [42]	N/A	N/A	Higher in-hospital mortality risk in smokers	N/A	N/A	N/A	N/A	N/A
Minh, LHN [43]	More in smokers	Higher risk of severity in smokers	Higher death risk in smokers	N/A	N/A	N/A	N/A	N/A
Patanavanich, R [44]	Higher disease progression in those with a history of smoking	N/A	Increased risk of death from COVID-19	N/A	N/A	N/A	N/A	N/A
Patanavanich, R [45]	N/A	N/A	Higher risk of death in current and former smokers compared to never smokers	N/A	N/A	N/A	N/A	The risk for COVID-19 death in current smokers does not vary by age, but significantly drops by age in former smokers
Plasencia-Urizarri, TM [46]	N/A	Higher risk for severe clinical presentations in smokers	N/A	N/A	N/A	N/A	N/A	N/A
Pranata, R [47]	N/A	N/A	Increased risk of composite poor outcome in smoker	N/A	N/A	N/A	N/A	Current smokers were at higher risk of composite poor outcomes than former/nonsmokers
Reddy, RK [28]	Increased risk of disease progression in patients with a smoking history	Increased risk of severe COVID-19 in current smokers	Increased in-hospital mortality in patients with a smoking history	N/A	N/A	N/A	Increased need for mechanical ventilation in patients with a smoking history	N/A
Sanchez-Ramirez, DC [48]	N/A	N/A	Higher rate of severe outcome in current and former smokers	N/A	N/A	N/A	N/A	N/A
Taylor, EH [49]	N/A	N/A	Higher ICU mortality rate in smokers	N/A	N/A	N/A	N/A	N/A
Umnuaypornlert, A [50]	N/A	Increased risk of disease severity in current and former smokers	Increased mortality in current and former smokers	N/A	N/A	N/A	N/A	N/A
Vardavas, C.I [18]	Smokers are more prone to have negative progression and severe symptoms	Smokers have severe disease	Higher mortality rate and adverse outcome was seen in smokers	More in smokers	N/A	Higher risk of ICU admission in smoker group	Higher risk of MV in smokers	There is an association between smoking and higher mortality and adverse outcome
Zhang, H [51]	N/A	Smoking was associated with severe COVID	Smokers have higher mortality rate	N/A	N/A	Higher risk of ICU admission was seen among smokers	No relationship was found between MV and smoking	Severe disease was more associated with former smoking compared to current smoking
Zhang, T [52]	Former smokers have more symptoms and severe disease	Former smokers are more prevalent in severe COVID group	Higher mortality rate is seen in severe cases (including former smokers)	N/A	N/A	N/A	N/A	Smoking is among the risk factors for severe COVID infection and complications