The Paradox of the Low Prevalence of Current Smokers Among COVID-19 Patients Hospitalized in Nonintensive Care Wards: Results From an Italian Multicenter Case-Control Study

Introduction: COVID-19, a respiratory illness due to SARS-CoV-2 coronavirus, was first described in December 2019 in Wuhan, rapidly evolving into a pandemic. Smoking increases the risk of respiratory infections; thus, cessation represents a huge opportunity for public health. However, there is scarce evidence about if and how smoking affects the risk of SARS-CoV-2 infection.Methods: We performed an observational case-control study, assessing the single-day point prevalence of smoking among 218 COVID-19 adult patients hospitalized in seven Italian nonintensive care wards and in a control group of 243 patients admitted for other conditions to seven COVID-19-free general wards. We compared proportions for categorical variables by using the chi(2) test and performed univariate and multivariate logistic regression analyses to identify the variables associated with the risk of hospitalization for COVID-19.Results: The percentages of current smokers (4.1% vs 16%, p= .00003) and never smokers (71.6% vs 56.8%, p = .0014) were significantly different between COVID-19 and non-COVID 19 patients. COVID-19 patients had lower mean age (69.5 vs 74.2 years, p= .00085) and were more frequently males (59.2% vs 44%, p = .0011). In the logistic regression analysis, current smokers were significantly less likely to be hospitalized for COVID-19 compared with nonsmokers (odds ratio = 0.23; 95% confidence interval, 0.11-0.48, p< .001), even after adjusting for age and gender (odds ratio = 0.14; 95% confidence interval, 0.06-0.31, p < .001).Conclusions: We reported an unexpectedly low prevalence of current smokers among COVID-19 patients hospitalized in nonintensive care wards.The meaning of these preliminary findings, which are in line with those currently emerging in literature, is unclear; they need to be confirmed by larger studies.