# Impact of Smoking and Deprivation in Patients Admitted With Severe COVID-19 Infection to ICU: A Retrospective Cohort Study

## TL;DR

This study finds that current smokers admitted to ICU with severe COVID-19 tend to be from deprived areas and have worse survival outcomes.

## Contribution

The study identifies a link between smoking, social deprivation, and higher mortality in severe COVID-19 ICU patients.

## Key findings

- Current smokers admitted to ICU with severe COVID-19 had longer hospital and ICU stays.
- Current smokers were from the most deprived areas and had reduced survival rates.
- Smoking prevalence in ICU was low (6.3%), but smokers had higher mortality risk.

## Abstract

Smoking is known to be harmful to health, contributing to increased severity in respiratory infections such as influenza. The impact in COVID-19 remains controversial. Social deprivation and inequality are associated with worse outcomes in infectious disease and may impact on mortality in COVID-19.

A retrospective cohort study in a tertiary hospital general adult Intensive Care Unit (ICU). 174 patients with COVID-19 confirmed by polymerase chain reaction (PCR) testing between March 21st 2020 and May 15th 2021 included. Data collection was by retrospective review of clinical notes. Patients were grouped into three categories: current smokers, former smokers (ex-smokers) and never smokers. Statistical analysis carried out on IBM Statistical Package for Social Sciences (SPSS) for Windows, version 28.0 (Armonk, NY:IBM Corp). Values reported as means, standard deviation (SD), median and interquartile ranges (IQR). Comparisons with the Mann–Whitney U test for median and IQR and two sample t-test for mean and SD. Survival analysis was performed using Kaplan–Meier.

Of 174 patients, 11 were current smokers (6.3%), 51 were former smokers (29%) and 112 were never smokers (64%). Current smokers were younger and frailer, with longer hospital and ICU length of stay (ICULOS). Welsh Index of Multiple Deprivation (WIMD) scores were collected using UK postcodes and ranked 1909 areas, showing current smokers from the most deprived areas. Kaplan–Meier survival analysis showed current smokers are less likely to survive.

Despite 6.3% prevalence of smoking in patients with severe COVID-19 in the ICU, smokers had increased hospital and ICU LOS with reduced survival. The relationship between COVID-19 and deprivation is multifaceted and complex and may relate to demographic, socioeconomic and environmental factors; health-related risk factors; and practices. From our data we can see that current smokers admitted to ICU with severe COVID-19 were from the most deprived areas in Wales, with a higher mortality risk.