Abstract
Introduction: Characterising the symptom profile of COVID-19 in smokers compared to non-smokers enables the identification of distinct clinical patterns and potential risk factors. This, in turn, supports more accurate risk stratification and the formulation of targeted public health strategies, particularly within primary care settings, where early detection and timely intervention are essential.
Material and Methods: A population-based, cross-sectional comparative study was conducted using national surveillance data from 475 healthcare units across Mexico. The analysis focused on patients tested for SARS-CoV-2, stratified by smoking status (smokers and non-smokers). Variables included age, clinical symptoms, comorbidities, test results, and vaccination status. Associations between symptoms, comorbidities, and COVID-19 positivity were assessed using multivariate logistic regression models in both groups.
Results: The study included two groups: a total of 48,314 smokers (12.5%; 95% CI 12.4-12.6) and 338,900 non-smokers patients (87.5%; 95% CI 87.4-87.6), resulting in a total study population of 387,214 patients. From this population, we identified 193,607 patients with COVID-19 (21,777 smokers versus 171,830 non-smokers patients). Smokers exhibited a higher prevalence of all reported symptoms in comparison to non-smokers: headache (62% vs 60.3%), cough (57.7% vs 56.6%), myalgia (42.9% vs 39.7%) and odynophagia (40.4% vs 36.9), with the exception of fever (41.3% vs 43.4%). Signs and symptoms positively associated with a higher likelihood of COVID-19 in both smokers and non-smokers included fever, cough, dyspnoea, chest pain, chills, myalgia, arthralgia, malaise, rhinorrhoea, polypnoea, and cyanosis. In contrast, type 2 diabetes, obesity, and hypertension were linked to an increased risk of COVID-19 only among non-smokers. Age showed an inverse relationship with COVID-19 risk in both groups. Notably, being female was the only factor consistently associated with a higher risk of infection across both populations.
Conclusion: The observed profile among smokers suggests a more symptomatic or severe clinical presentation. The lack of association among obesity, hypertension, and diabetes with COVID-19 in this group suggests a possible existence of distinct biological or behavioural mechanisms influencing disease susceptibility and progression.