key: cord-0824020-pouric28
authors: Karanasos, Antonios; Aznaouridis, Konstantinos; Latsios, George; Synetos, Andreas; Plitaria, Stella; Tousoulis, Dimitrios; Toutouzas, Konstantinos
title: Impact of smoking status on disease severity and mortality of hospitalized patients with COVID-19 infection: a systematic review and meta-analysis
date: 2020-06-20
journal: Nicotine Tob Res
DOI: 10.1093/ntr/ntaa107
sha: 672fc877fe59e180a51674d4eb203da3ef3df7b7
doc_id: 824020
cord_uid: pouric28

nan

review and meta-analysis to summarize relevant studies and quantify the impact of smoking on disease severity and mortality of hospitalized COVID-19 patients.

The primary outcome was a composite for disease severity including severe disease (including critical cases), ICU admission or invasive ventilation, and adverse disease progression or refractory disease. The secondary outcome was death. Inclusion criteria were: Table) . Study quality was generally low (Figure 1; Online supplement) . Our main findings were 1) that smoking modestly increases the risk of severe disease in hospitalized COVID-19 patients while mortality data demonstrate a similar effect size but are currently inconclusive due to a low sample size, and 2) that this increased risk for disease severity is more prominent in younger patients without diabetes. Although most patients were from China, a considerable number of USA patients were included, notably with evidence of regional differences. This difference may be explained by the higher age and diabetes ratio of the non-Chinese population, which we showed to be important risk moderators, or could be due to further differences in comorbidities and care. Therefore, updated studies more representative of the global population are urgently needed.

Our study had several limitations. This metanalysis is prone to bias attributed to the included retrospective studies which relied on poor quality data and did not specifically investigate the impact of smoking. However, due to the nature of the analysis and the need to quickly gain insights into COVID-19 infection mechanisms, it is unlikely that prospective, high-quality studies will be available soon. Moreover, study heterogeneity was low-to-A c c e p t e d M a n u s c r i p t 5 moderate and sensitivity analyses were consistent. The number of included studies and patients for the endpoint of mortality is small and more data are required to properly examine this association. Finally, despite screening included studies for duplicate patients, we cannot exclude the possibility that some patients, especially in nationwide registries, were reported twice.

In summary, current data suggest a possible adverse impact of smoking on disease severity and mortality of hospitalized COVID-19 patients, which is more pronounced in younger patients without diabetes. Further data more representative of the global population are required to corroborate these preliminary findings.

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