The association of smoking status with SARS-CoV-2 infection, hospitalisation and mortality from COVID-19: A living rapid evidence review with Bayesian meta-analyses (version 11)

Abstract

Aims: To estimate the association of smoking status with rates of i) infection, ii) hospitalisation, iii) disease severity, and iv) mortality from SARS-CoV-2/COVID-19 disease.Design: Living rapid review of observational and experimental studies with random-effects hierarchical Bayesian metaanalyses. Published articles and pre-prints were identified via MEDLINE and medRxiv.Setting: Community or hospital. No restrictions on location.Participants: Adults who received a SARS-CoV-2 test or a COVID-19 diagnosis.Measurements: Outcomes were SARS-CoV-2 infection, hospitalisation, disease severity and mortality stratified by smoking status. Study quality was assessed (i.e. 'good', 'fair' and 'poor').Findings: v11 (searches up to 2021-02-16) included 405 studies with 62 'good' and 'fair' quality studies included in unadjusted meta-analyses. 121 studies (29.9%) reported current, former and never smoking status with the remainder using broader categories. Recorded smoking prevalence among people with COVID-19 was generally lower than national prevalence. Current compared with never smokers were at reduced risk of SARS-CoV-2 infection (RR = 0.71, 95% Credible Interval (CrI) = 0.61-0.82, τ = 0.34). Data for former smokers were inconclusive (RR = 1.03, 95% CrI = 0.95-1.11, τ = 0.17) but favoured there being no important association (4% probability of RR ≥1.1). Former compared with never smokers were at increased risk of hospitalisation (

Smoking and COVID-19: current evidence from Italy and the world

“…The prevalence of smokers was quite heterogeneous, ranging from 0% to 70% in Asia, from 0% to 23% in Europe, and from 1% to 35% in the Americas. More importantly, smoking prevalence was systematically lower than adult prevalence estimates observed in countries where the studies were conducted [2]. This suggested that smoking could have a protective role on the incidence of SARS-CoV-2 infection.…”

“…È necessario invece basarsi sul crescente numero di studi di coorte che indagano l'incidenza di COVID-19 e che sono condotti sulla popolazione generale. Simons e coll., in una metanalisi -basata su questo tipo di studi e aggiornata a marzo 2021 [2] -hanno mostrato come, rispetto a coloro che non avevano mai fumato, i fumatori hanno un rischio relativo, RR, di 0,71 (intervallo di confidenza, CI, al 95%: 0,61-0,82) e gli ex fumatori di 1,03 (95% CI: 0,95-1,11). Per quanto riguarda invece la gravità e mortalità per COVID-19, ci sono meno dubbi: i fumatori hanno più frequentemente un decorso sfavorevole della malattia rispetto ai non fumatori [3,4].…”

“…Instead, evidence should be built on the increasing number of cohort studies investigating the incidence of SARS-CoV-2 infection on samples based on the general population. Simons et al, in a meta-analysis -based on this type of studies, updated in March 2021 [2], showed how, compared to never smokers, current smokers have a relative risk, RR, of 0.71 (confidence interval, CI, 95%: 0.61-0.82) and ex-smokers of 1.03 (95% CI: 0.95-1.11) of being infected with SARS-CoV-2. For what concerns COVID-19 severity and mortality, the evidence is more robust: compared to non-smokers, current smokers have more frequently an unfavourable progression of the disease [3,4].…”

“…La prevalenza di fumatori, variando da 0 al 70% in Asia, da 0 al 23% in Europa e dall'1 al 35% nelle Americhe, risultava piuttosto eterogenea. Più importante, la prevalenza di fumo era sistematicamente molto inferiore rispetto alle stime di prevalenza tra gli adulti dei Paesi dove erano stati condotti gli studi [2]. Questo aveva fatto pensare che il fumo potesse avere un ruolo protettivo per l'incidenza della infezione da SARS-CoV-2.…”

ENE-COVID nationwide serosurvey served to characterize asymptomatic infections and to develop a symptom-based risk score to predict COVID-19

“…A certain underdetection of cases among smokers could not be ruled out, since they may develop lower antibody levels. 31 However, a recent review concluded that smokers have lower risk of infection, 32 although the mechanisms are not well understood. 33 A lower probability of participation of infected smokers in our study due to their higher risk of hospitalization is unlikely, as we contacted each person up to 3 times -one per round-, so they had several chances to participate.…”