# Severe COVID-19 in Non-Smokers: Predictive Factors and Outcomes

## TL;DR

This study identifies factors predicting mortality in non-smoking patients with severe COVID-19, emphasizing the importance of ventilation strategies and Day 7 SOFA scores.

## Contribution

The study provides specific mortality predictors for non-smoking severe COVID-19 patients using clinical and oxygenation parameters.

## Key findings

- The seventh-day SOFA score was the strongest predictor of mortality (AUC = 0.902).
- Mortality rates varied significantly with ventilation type: 84.6% for IMV and 50% for NIMV.
- Acid-base parameters and oxygenation indices differed significantly between survivors and non-survivors.

## Abstract

Background: The COVID-19 pandemic revealed an unexpected pattern known as the “smoker’s paradox”, with lower rates of severe disease among smokers compared to non-smokers, highlighting the need for the specific investigation of disease progression in non-smoking populations. Objective: To identify early mortality predictors in non-smoking patients with severe COVID-19 through the evaluation of clinical, laboratory, and oxygenation parameters. Methods: This retrospective observational cohort study included 59 non-smokers hospitalized with COVID-19 between November and December 2020. Clinical parameters, laboratory findings, and respiratory support requirements were analyzed on Days 1 and 7 of hospitalization. ROC curves were constructed to assess the predictive value of the parameters. Results: The overall mortality rate was 54.2%. The seventh-day SOFA score showed the strongest predictive value (AUC = 0.902, p = 0.004), followed by pCO2 (AUC = 0.853, p = 0.012). Significant differences between survivors and non-survivors were observed in acid–base parameters, oxygenation indices, and hematological markers. Mortality rates varied significantly with ventilation type: 84.6% for IMV and 50% for NIMV, with no deaths in HFNC patients. Conclusions: Multiple parameters measured on Day 7 of hospitalization demonstrate significant predictive value for mortality in non-smoking COVID-19 patients, with the SOFA score being the strongest predictor. The type of respiratory support significantly influences outcomes, suggesting the importance of careful ventilation strategy selection.