(1358) Association of Smoking and Mortality in ICU Patients With COVID-19: A Population-Based Study

Introduction: Smoking is associated with lower life expectancy and patients with a history of smoking are at increased risk of diseases of the respiratory system. Data on the prognostic impact of smoking on critically-ill patients with COVID-19 is inconclusive.

Methods: We used publicly available, statewide, and deidentified hospitalization records to study patients aged ≥18 years with a diagnosis of COVID-19 admitted to the intensive care unit (ICU) at acute care hospitals in Texas for from Q2 2020 through Q1 2022. Patients with a history of smoking were identified using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes F17200 and Z8789. Hospitalizations with a diagnosis of COVID-19 were identified using ICD-10-CM code U071. Three models estimated the association between smoking and in-hospital mortality. Multilevel logistic regression with propensity adjustment was the primary analysis approach with propensity score matching and multivariable logistic regression applied as alternative analyses. Additional analyses were completed for patient subgroups and for the secondary outcome of short-term mortality.

Results: Out of 252,602 ICU hospitalizations with a diagnosis of COVID-19, 41,755 (16.5%) had a history of smoking. COVID-19 hospitalizations with vs without a history of smoking were older (54.4% vs 44.1% aged ≥ 65 years), more often male (64.7% vs 52.5%), more frequently had chronic lung disease (30.2% vs 15.9%) and had higher Deyo comorbidity index (mean [SD] 1.71[1.88] vs 1.42[1.85]); p < 0.0001 for each. Unadjusted in-hospital mortality for COVID-19 ICU patients with and without a history of smoking was 17.6% vs 21.1%. On adjusted analyses, smoking remained associated with lower odds of short-term mortality (adjusted odds ratio 0.8943 [95% CI 0.8624–0.9274]). The results were similar for the alternative modeling approaches, subgroup analyses, and the secondary outcome of short-term mortality.

Conclusions: A history of smoking was associated with a lower risk of both in-hospital and short-term mortality for ICU patients with a diagnosis of COVID-19. Studies exploring the mechanisms leading to these findings will improve understanding of the impacts of a history of smoking on the disease process of COVID-19.