Comorbidities are associated with the severity of coronavirus disease 2019 . This meta-analysis aimed to explore the risk of severe COVID-19 in patients with pre-existing chronic obstructive pulmonary disease (COPD) and ongoing smoking history. A comprehensive systematic literature search was carried out to find studies published from December 2019 to 22 March 2020 from five databases. The languages of literature included English and Chinese. The point prevalence of severe COVID-19 in patients with pre-existing COPD and those with ongoing smoking was evaluated with this meta-analysis. Overall 11 case series, published either in Chinese or English language with a total of 2002 cases, were included in this study. The pooled OR of COPD and the development of severe COVID-19 was 4.38 (fixed-effects model; 95% CI: 2.34-8.20), while the OR of ongoing smoking was 1.98 (fixed-effects model; 95% CI: 1.29-3.05). There was no publication bias as examined by the funnel plot and Egger's test (P = not significant).The heterogeneity of included studies was moderate for both COPD and ongoing smoking history on the severity of COVID-19. COPD and ongoing smoking history attribute to the worse progression and outcome of COVID-19.COPD, COVID-2019, smoking 2.34-8.20), heterogeneity among the different studies being moderate (I 2 = 41%; P = .08). Sensitivity analysis showed that the results were not affected by any individual study. Publication bias, as accessed by funnel plot ( Figure 2B) and Egger's test, showed no publication bias in this analysis (P for Egger's test was 0.5492). | Pre-existing COPD and mortalityOnly two of the included studies reported the association between death and pre-existing COPD. 11,12 Death was reported in 6 of 10 (60%) of patients with COPD and 80 of 233 (34.3%) of non-COPD patients. The pooled OR of COPD for death was 1.93 (95%CI: 0.59-7.43); however, the heterogeneity in this analysis (I 2 = 61%; P = .11) was quite high. | Smoking history and the severity of COVID-19Seven studies reported the relationship between active smoking and the severity of 8,[11][12][13]16,17 The exact duration of smoking was not reported in most studies. The pooled OR is summarized in Figure 2C, which shows that smoking increases the risk of severe COVID-19 (fixed-effects model; OR = 1.98; 95% CI: 1.29-3.05) by around twofolds. The heterogeneity among the different studies was moderate (I 2 = 44%; P = .10). Sensitivity analysis by excluding each study one by one showed that the study from Guan 6 was a major source of heterogeneity. After excluding this F I G U R E 3 Subgroup analysis for the impact of COPD and smoking histology on the severity of COVID-19. CI, confidence interval; COPD, chronic obstructive pulmonary disease; COVID-19, coronavirus disease 2019; ICU, intesive care unit; OR, odds ratio ZHAO ET AL.| 5 overall sample size could be a possible explanation. When the study with the largest sample size was excluded from sensitivity analysis, the effect of smoking on the severity of COVID-19 was no longer significant. An...

Objectives: Coronavirus Disease 2019 is a new respiratory and systemic disease which needs quick identification of potential critical patients. This meta-analysis aimed to explore the relationship between lymphocyte count and the severity of COVID-19. Methods: A comprehensive systematic literature search was carried out to find studies published from December 2019 to 22 March 2020 from five databases. The language of literatures included English and Chinese. Mean difference (MD) of lymphocyte count in COVID-19 patients with or without severe disease and odds ratio (OR) of lymphopenia for severe form of COVID-19 was evaluated with this meta-analysis. Results: Overall 13 case-series with a total of 2282 cases were included in the study. The pooled analysis showed that lymphocyte count was significantly lower in severe COVID-19 patients (MD -0.31 Â10 9 /L; 95%CI: -0.42 to -0.19 Â 10 9 /L). The presence of lymphopenia was associated with nearly threefold increased risk of severe COVID-19 (Random effects model, OR = 2.99, 95% CI: 1.31-6.82). Conclusions: Lymphopenia is a prominent part of severe COVID-19 and a lymphocyte count of less than 1.5 Â 10 9 /L may be useful in predicting the severity clinical outcomes.

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