Impact of smoking on COVID-19 outcomes: a HOPE Registry subanalysis

Background Smoking has been associated with poorer outcomes in relation to COVID-19. Smokers have higher risk of mortality and have a more severe clinical course. There is paucity of data available on this issue, and a definitive link between smoking and COVID-19 prognosis has yet to be established. Methods We included 5224 patients with COVID-19 with an available smoking history in a multicentre international registry Health Outcome Predictive Evaluation for COVID-19 (NCT04334291). Patients were included following an in-hospital admission with a COVID-19 diagnosis. We analysed the outcomes of patients with a current or prior history of smoking compared with the non-smoking group. The primary endpoint was all-cause in-hospital death. Results Finally, 5224 patients with COVID-19 with available smoking status were analysed. A total of 3983 (67.9%) patients were non-smokers, 934 (15.9%) were former smokers and 307 (5.2%) were active smokers. The median age was 66 years (IQR 52.0-77.0) and 58.6% were male. The most frequent comorbidities were hypertension (48.5%) and dyslipidaemia (33.0%). A relevant lung disease was present in 19.4%. In-hospital complications such sepsis (23.6%) and embolic events (4.3%) occurred more frequently in the smoker group (p<0.001 for both). All cause-death was higher among smokers (active or former smokers) compared with non-smokers (27.6 vs 18.4%, p<0.001). Following a multivariate analysis, current smoking was considered as an independent predictor of mortality (OR 1.77, 95% CI 1.11 to 2.82, p=0.017) and a combined endpoint of severe disease (OR 1.68, 95% CI 1.16 to 2.43, p=0.006). Conclusion Smoking has a negative prognostic impact on patients hospitalised with COVID-19.