Low rate of daily active tobacco smoking in patients with symptomatic COVID-19

Abstract
Importance: As the pandemic of COVID-19 is still under progression, identification of prognostic factors remains a global challenge. The role of smoking has been suggested among the disease risk factors, although it is highly controversial. Objective: To evaluate whether the rate of daily smokers in patients with COVID-19 was different to that in the French population. Participants: COVID-19-infected in- and outpatients in a large French university hospital between February 28, 2020 and March 30, 2020 for outpatients and from March 23, till April 9, 2020 for inpatients. Design: We systematically interviewed the patients on their smoking status, use of e-cigarette and nicotinic substitutes. The rate of daily smokers in inpatients and outpatients were compared to those in the 2018 French general population, after standardization for sex and age. Results: The inpatient group was composed of 340 patients, median age 66 years: 203 men (59.7%, median age 66 years) and 137 women (40.3%, median age 66 years),with a rate of daily smokers of 4.1% CI95% [2.3 – 6.9] (5.4% of men and 2.2% of women). The outpatient group was composed of 139 patients, median age 44 years: 62 men (44.6%, median age 43 years, and 77 women (55.4 %, median age 44 years). The daily smokers’ rate was 6.1 % CI95% [2.7 - 11.6] (5.1% of men and 6.8 % of women). In the French population, the daily smokers’ rate was 25.4% (28.2% of men and 22.9% of women). The rate of daily smokers was significantly lower in COVID-19 patients, as compared to that in the French general population after standardization by age and sex, with Standardized Incidence Ratios of 0.23 [0.11 - 0.45] for outpatients and 0.23 [0.14 - 0.39] for inpatients. These ratios did not significantly differ between the two groups (P=0.94). Conclusions and relevance: This cross sectional study in both COVID-19 out- and inpatients shows that daily smokers rate in patients with symptomatic COVID-19 is lower as compared to the general population.