Relationship between digestive diseases and COVID-19 severity and mortality: A protocol for systematic review and meta-analysis.

Background: Digestive diseases have been often reported in COVID-19 patients, but whether COVID-19 patients with existing digestive comorbidities are at an increased risk of serious disease and death remains unclear. This study aims to evaluate the association between digestive diseases and COVID-19 severity and mortality.

Methods: PubMed, Embase.com, the Cochrane Central Register of Controlled Trials, Web of Science, China National Knowledge Infrastructure, Wanfang, and SinoMed will be searched to identify relevant studies up to October 1, 2020. We will use the Newcastle-Ottawa quality assessment scale to assess the quality of included studies. We will use Stata to perform pairwise meta-analyses using the random-effects model with the inverse variance method to estimate the association between digestive diseases and the mortality and severity of COVID-19. Subgroup analyses and sensitivity analyses will be conducted to investigate the sources of heterogeneity. We will create a "Summary of findings' table presenting our primary and secondary outcomes using the GRADEpro Guideline Development Tool software.

Results: The results of this study will be published in a peer-reviewed journal.

Conclusions: This study will comprehensively evaluate the association between digestive diseases and the severity and mortality of patients with COVID-19. The results of this study will provide high-quality evidence to support clinical practice and guidelines development.