Does Timing of Smoking Cessation Have an Impact on Covid-19 Outcomes?

ABSTRACT

INTRODUCTION: The relationship between smoking and increased morbidity/mortality with COVID19 is well documented;however, there is little data on the relationship between former smokers (FS) and COVID19. Risk stratification of FS is dependent on years since smoking cessation (SC). We conducted a study to determine, if years since SC influenced COVID19 outcomes. METHOD(S) A retrospective cohort study at a single institution. Inclusion criteria age >= 18 and admitted to the hospital from Jan 2020 to Nov 2021 for COVID19. Patients were divided into two categories;SC < 15 years, and SC > 15 years. The primary outcome was mortality, with secondary outcomes: requirement of nasal cannula (NC), NIV, and mechanical ventilation (MCV). Odds ratios (OR) were calculated for all outcomes. Post-hoc age-adjusted odds ratios (AOR) for age < 75, were calculated for all outcomes. Mortality data was collected on all patients, and OR were calculated between FS, smokers (CS), and non-smokers (NS). RESULT(S) The total number of patients was 608 with 256 being FS, 308 non-smokers, 30 CS, and 14 unknown smoking status. The mean age of FS was 70. There were 154 males (60%) 102 females (40%). Total FS < 75 was 152. Obesity rates were 64.1% and 67.6%, T2DM (Diabetes Mellitus) rates were 34.3% and 59.5% in SC < 15 and SC > 15, respectively. There was no difference in mortality between the two groups, OR (OR 0.81, CI 0.46-1.40, p=0.45) and AOR (AOR 0.79, 0.37-1.69, p=0.54). There was an increased risk of MCV for the SC < 15 group (OR 2.1, CI 1.02-4.57, p=0.04). AOR did not replicate this trend. There was no difference in patients requiring NC (AOR 1.38, CI 0.70-2.74, p=0.36) or MCV (AOR 1.65, CL 0.69- 3.91, p=0.25) between the two groups. SC < 15 had lower rates of NIV (AOR 0.36, CI 0.15-0.90, p=0.029). There was no difference in mortality between FS and CS (OR 1.69, CI 0.70-4.19, p=0.24). The FS group had higher rates of mortality than NS (OR 1.43, CI 1.00-2.05, p=0.048). CONCLUSION(S) Regardless of the timing of SC, FS have the same mortality and MCV rates with COVID19. High comorbidity burden was noted in both population groups, with the SC > 15 group having higher rates of T2DM. Further studies are needed to determine the full effect of SC on COVID19 outcomes, including effect of pack years.