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Although many studies have reported cases of COVID-19 infection in transplant recipients, most of them only involve a small number of patients and narrow geographic areas. This study aims to investigate the clinical characteristics, morbidity, severity, and mortality of COVID-19 infection among solid organ transplant (SOT) recipients by meta-analysis. We performed a literature search using the databases PubMed, Web of Science, and Google Scholar as of November 26, 2020. We included randomized controlled trials and cohort studies, excluding case reports and small case series (n < 10). The pooled incidence proportion and 95% confidence intervals (CI) were used to estimate the combined results of forty-seven studies were included for the meta-analysis. Heterogeneity was assessed using I². Freeman-Tukey double arcsine transformation was used to stabilize the specific rate variance. Publication bias was using Egger’s test. The morbidity rate of COVID-19 in SOT recipients was 2.10% [95% CI 1.35–3.01], and the proportion of severe infection was 22.46% [95% CI 15.74–29.90]. The mortality rate was 17.38% [95% CI 13.72–21.34]. In the analysis by transplanted organ, the proportion of patients with severe infection was highest in recipients of two or more transplants 48.85% [95% CI 11.88–86.38]. The mortality rate was highest in lung transplant recipients 25.12% [95% CI 16.94–34.00]. The most common symptoms of COVID-19 in SOT recipients were fever (73.39%), cough (58.90%), and respiratory symptoms (45.77%). SOT was a risk factor for worse COVID-19 outcomes, although the morbidity of COVID-19 in SOT recipients was not markedly higher than the general population. These results may change when our understanding of the disease progress.

To systematically investigate the relationship between cardiac biomarkers and COVID-19 severity and mortality. We performed a literature search using PubMed, Web of Science, and Google Scholar. The standardized mean difference (SMD) and 95% confidence interval (CI) were applied to estimate the combined results of 67 studies. A meta-analysis of cardiac biomarkers was used to evaluate disease mortality and severity in COVID-19 patients. A meta-analysis of 7812 patients revealed that patients with high levels of cardiac troponin I (SMD = 0.81 U/L, 95% CI = 0.14–1.48, P = 0.017), cardiac troponin T (SMD = 0.78 U/L, 95% CI = 0.07–1.49, P = 0.032), high-sensitive cardiac troponin I (SMD = 0.66 pg/mL, 95% CI = 0.51–0.81, P < 0.001), high-sensitive cardiac troponin T (SMD = 0.93 U/L, 95% CI = 0.21–1.65, P = 0.012), creatine kinase-MB (SMD = 0.54 U/L, 95% CI = 0.39−0.69, P < 0.001), and myoglobin (SMD = 0.80 U/L, 95% CI = 0.57–1.03, P < 0.001) were associated with prominent disease severity in COVID-19 infection. Moreover, 9532 patients with a higher serum level of cardiac troponin I (SMD = 0.51 U/L, 95% CI = 0.37–0.64, P < 0.001), high-sensitive cardiac troponin (SMD = 0.51 ng/L, 95% CI = 0.29–0.73, P < 0.001), high-sensitive cardiac troponin I (SMD = 0.51 pg/mL, 95% CI = 0.38–0.63, P < 0.001), high-sensitive cardiac troponin T (SMD = 0.85 U/L, 95% CI = 0.63–1.07, P < 0.001), creatine kinase-MB (SMD = 0.48 U/L, 95% CI = 0.32–0.65, P < 0.001), and myoglobin (SMD = 0.55 U/L, 95% CI = 0.45−0.65, P < 0.001) exhibited a prominent level of mortality from COVID-19 infection. Cardiac biomarkers (cardiac troponin I, cardiac troponin T, high-sensitive cardiac troponin, high-sensitive cardiac troponin I, high-sensitive cardiac troponin T, creatine kinase-MB, and myoglobin) should be more frequently applied in identifying high-risk COVID-19 patients so that timely treatment can be implemented to reduce severity and mortality in COVID-19 patients.