A total of 577 patients were admitted to our institution with COVID-19 from March 15th, 2020 to May 06th, 2020 and are included in the analysis. Based on smoking status, there were 309 (53.5%) nonsmokers, 187 (32.4%) former smokers with a median pack-years of 21.7 (IQR 12.3-40) and 81 (14%) active smokers with a median of 20 pack-years (IQR 10.8-35), Table 1 shows the demographics, clinical, laboratory and hospitalization characteristics on the patients comparing nonsmokers to former and active smokers.
Patient demographics:
The mean age was 59 ±16 years for the study population, former smokers were older compared to nonsmokers and active smokers. There was no gender predominance across the groups. African Americans (AA) were the predominant race; the number of AA active and former smokers was higher compared to AA nonsmokers (p<0.0001). Mean BMI was 31.5 ± 7.8 with no differences between the groups.
Comorbidities:
Hypertension (66.5%), obesity (48.5%), diabetes (42.2%) and psychiatric disorders (21.6%) were the most common comorbidities detected. Compared to nonsmokers, former smokers had significantly more comorbidities such as hypertension, diabetes, coronary artery disease, heart failure, COPD, psychiatric disorder and substance abuse. Active smokers were less obese, and had a greater percentage of patients with a history of COPD, psychiatric disorder and polysubstance abuse when compared to none smokers. Former smokers when compared to active smokers had a greater reported history of cardiometabolic and cerebrovascular disease (Table 2. Supplementary file).
Biomarkers of inflammation:
In never smokers the median D Dimer was 722.5 ng/mL (IQR: 450-1172ng/mL) when compared to former smokers 1074.5ng/mL (IQR: 578-2077ng/mL) (p<0.0001) and active smokers 931.5ng/mL (IQR: 475-2043ng/mL) (p=0.05) was significantly elevated. CRP and ferritin values were not significantly different.
Oxygen requirements and intubation:
When comparing the oxygen requirements on an ordinal scale at admission, former smokers had a higher need for HFNT and BiPAPÔ compared to nonsmokers. (Table 3. Supplementary file)
Active smokers had higher rates of mechanical ventilation when compared to nonsmokers upon admission (6.1% versus 2.7 %, p=0.16) and during hospitalization (19.8% versus 10.4%, p= 0.010). A sub-analysis of mechanically ventilated active smokers (n=16) showed that apart from COVID-19, there were other factors leading to mechanical ventilation such as drug abuse, encephalopathy or alcohol withdrawal in 7 patients (43%), pulmonary edema or ineffective dialysis in 2 (12.5%), metastatic malignancy in 2 (12.5%) and suicidal attempt in 1 (6.25%).
In a regression analysis model performed, there was a greater need for intubation in active smokers during hospitalization, odds ratio (OR) 2.09 (CI 95% 1.05-4.15, p<0.05) when compared to nonsmokers. In former smokers, even though there was a higher risk, the difference was not statistically significant, OR 1.46 (CI 95% 0.84-2.55, p=0.17). (Table 4)
ICU care:
A total of 155 (26.8%) of all patients required ICU care. There was a significant increase in the need for ICU care in former smokers when compared to nonsmokers (32.1% versus 22.7%, p<0.05). Active smokers had a slight increase in the need for ICU care when compared to nonsmokers (30.8% versus 22.7%, p=0.191), but this was not significant.
Mortality:
A total of 52 (9%) patients died at the time of data analysis. There was a significant increase in deaths in former smokers compared to nonsmokers (14.4% versus 7.2%, p<0.05) and to active smokers (14.4% versus 3.2%, p<0.05). Active smokers had a lower mortality compared to nonsmokers (3.2 versus 6.7%, p=0.264) but this was not significant.
On our regression analysis, former smokers had higher mortality with an OR of 1.99 (CI 95% 1.03-3.85, p<0.05) compared to nonsmokers. There was no increased risk of mortality for active smokers when compared to nonsmokers OR of 0.53 (CI95% 0.15-2.03, p<0.05). The presence of malignancy, age more than 65 years, chronic kidney disease, respiratory rate greater than 20 on admission and absolute lymphocyte count less than 1000 per mm3 were associated with higher mortality. (Table 5)