Evidence map›Paper›PMID 32749705›Full record

SynthesisJournal of medical virology2021

The effect of smoking on COVID-19 severity: A systematic review and meta-analysis.

Rohin K Reddy, Walton N Charles, Alexandros Sklavounos, Atul Dutt, Paul T Seed, Ankur Khajuria

Registry-linked trialAbstract readMeta-AnalysisSystematic Review
PubMed Full text at PMC Publisher
In one paragraph

Synthesis in Journal of medical virology, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT05102708 (Study of COVID-19 Prognostic Factors in Hospitalized Patients), which is not on this map. Cited by 240 papers, 7 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
240citing papers in PubMed, 7 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT05102708 completednot on this map

Study of COVID-19 Prognostic Factors in Hospitalized Patients

TypeobservationalSponsorFundació Institut de Recerca de l'Hospital de la Santa Creu i Sant PauRan2021 to 2022Enrolled3,725ConditionsCOVID-19ArmsPrognostic factors of severe COVID-19
3 · Its place in the literature

Who cites it

240 citing papers in PubMed, 7 syntheses or guidelines pooled it.

  1. Pooled it
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  3. The role of smoking in COVID-19 progression: a comprehensive meta-analysis.European respiratory review : an official journal of the European Respiratory Society · 2023
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  16. Risk factors for death by COVID-19, public hospital in Ciudad Juárez, México.Revista medica del Instituto Mexicano del Seguro Social · 2026
    Observational
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180 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

6 authors.

Rohin K ReddyDepartment of Surgery and Cancer, Imperial College London, London, UK.ORCID 0000-0002-4726-157X
Walton N CharlesDepartment of Surgery and Cancer, Imperial College London, London, UK.
Alexandros SklavounosDepartment of Women and Children's Health, King's College London, London, UK.
Atul DuttDepartment of Surgery and Cancer, Imperial College London, London, UK.
Paul T SeedDepartment of Women and Children's Health, King's College London, London, UK.
Ankur KhajuriaDepartment of Surgery and Cancer, Imperial College London, London, UK.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Various comorbidities represent risk factors for severe coronavirus disease 2019 (COVID-19). The impact of smoking on COVID-19 severity has been previously reported in several meta-analyses limited by small sample sizes and poor methodology. We aimed to rigorously and definitively quantify the effects of smoking on COVID-19 severity. MEDLINE, Embase, CENTRAL, and Web of Science were searched between 1 December 2019 and 2 June 2020. Studies reporting smoking status of hospitalized patients with different severities of disease and/or at least one clinical endpoint of interest (disease progression, intensive care unit admission, need for mechanical ventilation, and mortality) were included. Data were pooled using a random-effects model. This study was registered on PROSPERO: CRD42020180920. We analyzed 47 eligible studies reporting on 32 849 hospitalized COVID-19 patients, with 8417 (25.6%) reporting a smoking history, comprising 1501 current smokers, 5676 former smokers, and 1240 unspecified smokers. Current smokers had an increased risk of severe COVID-19 (risk ratios [RR]: 1.80; 95% confidence interval [CI]: 1.14-2.85; P = .012), and severe or critical COVID-19 (RR: 1.98; CI: 1.16-3.38; P = .012). Patients with a smoking history had a significantly increased risk of severe COVID-19 (RR: 1.31; CI: 1.12-1.54; P = .001), severe or critical COVID-19 (RR: 1.35; CI: 1.19-1.53; P < .0001), in-hospital mortality (RR: 1.26; CI: 1.20-1.32; P < .0001), disease progression (RR: 2.18; CI: 1.06-4.49; P = .035), and need for mechanical ventilation (RR: 1.20; CI: 1.01-1.42; P = .043). Patients with any smoking history are vulnerable to severe COVID-19 and worse in-hospital outcomes. In the absence of current targeted therapies, preventative, and supportive strategies to reduce morbidity and mortality in current and former smokers are crucial.

Indexed as

COVID-19HospitalizationHospital MortalityHumansIntensive Care UnitsRespiration, ArtificialRisk FactorsSmokingcoronavirusepidemiologypandemicspathogenesisrespiratory tractvirus classificationzoonoses

Identifiers

PMID32749705
PMCPMC7436545

What OpenQuestion holds

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Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.