INTRODUCTION COVID-19 has major effects on the clinical, humanistic and economic outcomes among patients, producing severe symptoms and death. Smoking has been reported as one of the factors that increases severity and mortality rate among COVID-19 patients. However, the effect of smoking on such medical outcomes is still controversial. This study conducted a comprehensive systematic review and meta-analysis (SR/MA) on the association between smoking and negative outcomes among COVID-19 patients. METHODS Electronic databases, including PubMed, EMBASE, Cochrane Library, Science Direct, Google Scholar, were systematically searched from the initiation of the database until 12 December 2020. All relevant studies about smoking and COVID-19 were screened using a set of inclusion and exclusion criteria. The Newcastle-Ottawa Scale was used to assess the methodological quality of eligible articles. Random meta-analyses were conducted to estimate odds ratios (ORs) with 95% confidence interval (CIs). Publication bias was assessed using the funnel plot, Begg's test and Egger's test. RESULTS A total of 1248 studies were retrieved and reviewed. A total of 40 studies were finally included for meta-analysis. Both current smoking and former smoking significantly increase the risk of disease severity (OR=1.58; 95% CI: 1.16-2.15, p=0.004; and OR=2.48; 95% CI: 1.64-3.77, p<0.001; respectively) with moderate appearance of heterogeneity. Similarly, current smoking and former smoking also significantly increase the risk of death (OR=1.35; 95% CI: 1.12-1.62, p=0.002; and OR=2.58; 95% CI: 2.15-3.09, p<0.001; respectively) with moderate appearance of heterogeneity. There was no evidence of publication bias, which was tested by the funnel plot, Begg's test and Egger's test. CONCLUSIONS Smoking, even current smoking or former smoking, significantly increases the risk of COVID-19 severity and death. Further causational studies on this association and ascertianing the underlying mechanisms of this relation is warranted.

中文翻译：

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COVID-19患者中的吸烟和阴性结果风险：系统评价和荟萃分析。

简介COVID-19对患者的临床，人文和经济结局具有重大影响，并产生严重的症状和死亡。据报道，吸烟是增加COVID-19患者病情严重程度和死亡率的因素之一。但是，吸烟对这种医学结果的影响仍存在争议。这项研究对COVID-19患者中吸烟与阴性结果之间的关系进行了全面的系统评价和荟萃分析（SR / MA）。方法从数据库启动到2020年12月12日，系统地搜索电子数据库，包括PubMed，EMBASE，Cochrane图书馆，Science Direct，Google Scholar。标准。纽卡斯尔-渥太华量表用于评估合格文章的方法学质量。进行随机荟萃分析以估计具有95％置信区间（CI）的比值比（OR）。使用漏斗图，Begg检验和Egger检验评估出版偏倚。结果共检索和审查了1248项研究。最终共纳入40项研究以进行荟萃分析。既往吸烟和以前吸烟均显着增加疾病严重程度的风险（OR = 1.58; 95％CI：1.16-2.15，p = 0.004; OR = 2.48; 95％CI：1.64-3.77，p <0.001;）中等程度的异质性外观。同样，现在吸烟和以前吸烟也显着增加了死亡风险（OR = 1.35； 95％CI：1.12-1.62，p = 0.002； OR = 2.58； 95％CI：2.15-3.09，p <0.001；分别具有中等程度的异质性外观。没有证据表明出版偏倚，这通过漏斗图，贝格检验和艾格检验进行了检验。结论吸烟，甚至现在或以前吸烟，都显着增加了COVID-19严重性和死亡的风险。有必要对这种关联进行进一步的因果关系研究，并确保这种关系的潜在机制。