3.1 Characteristics of the included studies:
The preliminary search reported 1689 articles. Seven hundred thirty-five
studies were included after removing duplicates. After considering the
title and abstract, 663 articles were eliminated, leaving 72 papers that
were regarded as plausible for this analysis. Following review of these
studies based on the inclusion and exclusion criteria, 30 articles
totaling 81,929 COVID-19 patients were eventually included in this
meta-analysis., Table 1 summarizes the baseline
characteristics of the included studies.