Lower Rate of Daily Smokers With Symptomatic COVID-19: A Monocentric Self-Report of Smoking Habit Study

Abstract

Background: Identification of prognostic factors in COVID-19 remains a global challenge. The role of smoking is still controversial. Methods: PCR-positive in- and outpatients with symptomatic COVID-19 from a large French University hospital were systematically interviewed for their smoking status, use of e-cigarette, and nicotinic substitutes. The rates of daily smokers in in- and outpatients were compared using the same smoking habit questionnaire to those in the 2019 French general population, after standardisation for sex and age. Results: The inpatient group was composed of 340 patients, median age of 66 years: 203 men (59.7%) and 137 women (40.3%), median age of both 66 years, with a rate of 4.1% daily smokers (CI 95% [2.3-6.9]) (5.4% of men and 2.2% of women). The outpatient group was composed of 139 patients, median age of 44 years: 62 men (44.6%, median age of 43 years) and 77 women (55.4%, median age of 44 years). The daily smoker rate was 6.1% (CI 95% [2.7-11.6], 5.1% of men and 6.8% of women). Amongst inpatients, daily smokers represented 2.2 and 3.4% of the 45 dead patients and of the 29 patients transferred to ICU, respectively. The rate of daily smokers was significantly lower in patients with symptomatic COVID-19, as compared to that in the French general population after standardisation by age and sex, with standardised incidence ratios (SIRs) of 0.24 [0.12-0.48] for outpatients and 0.24 [0.14-0.40] for inpatients. Conclusions: Daily smoker rate in patients with symptomatic COVID-19 is lower as compared to the French general population.

Keywords: COVID-19; SARS-CoV-2; cross sectional; smoking-epidemiology; tobacco.

Figure 1

Age and sex distribution in inpatients and outpatients with COVID-19. Dark- and light-shaded histograms represent nonadmitted (outpatients) and admitted (inpatients) patients with confirmed COVID-19 status, respectively. Red represents female patients and blue represents male patients.

Figure 2

Expected and observed number of cases of daily smokers amongst patients with COVID-19 (categorised by age and gender). (A) For outpatients. (B) For inpatients. The red bars represent female smokers and blue bars represent male smokers. The bars with lighter shading represent the expected number of daily smokers of each age and gender amongst the patients with COVID-19 in reference to 2019 French general population. The dark bars represent the observed number of daily smokers of each age and gender amongst the patients with COVID-19.