Inflammatory bowel disease and COVID-19 outcomes: a meta-analysis

There is conflicting evidence concerning the effect of inflammatory bowel disease (IBD) on COVID-19 incidence and outcome. Hence, we aimed to evaluate the published evidence through a systematic review process and perform a meta-analysis to assess the association between IBD and COVID-19. A compressive literature search was performed in PubMed/Medline, Scopus, Embase, and Cochrane Library from inception to July 2021. A snowball search in Google, Google Scholar, Research Gate, and MedRxiv; and bibliographic research were also performed to identify any other relevant articles. Quantitative observational studies such as cohort, cross-sectional, and case-control studies that assessed the incidence, risk, and outcomes of COVID-19 among the adult IBD patients published in the English language, were considered for this review. The incidence and risk of COVID-19, COVID-19 hospitalization, the severity of COVID-19, and mortality were considered as the outcomes of interest. The Joanna Briggs Institute critical appraisal checklist was used for quality assessment. A subgroup and sensitivity analysis were performed to explore the heterogeneity and robustness of the results, respectively. A total of 86 studies out of 2828 non-duplicate records were considered for this meta-analysis. The studies were single or multicentric internationally from settings such as IBD centres, medical colleges, hospitals, or from the general public. Most of the studies were observed to be of good quality with an acceptable risk of bias. The pooled prevalence of COVID-19, COVID-19 hospitalization, severe COVID-19, and mortality in the IBD population were 6.10%, 10.63%, 40.43%, and 1.94%, respectively. IBD was not significantly (p > 0.05) associated with the risk of COVID-19, COVID-19 hospitalization, severe COVID-19, and mortality. In contrast, ulcerative colitis was significantly associated with a higher risk of COVID-19 (OR 1.37; p = 0.01), COVID-19 hospitalization (OR 1.28; p < 0.00001), and severe COVID-19 (OR 2.45; p < 0.0007). Crohn's disease was significantly associated with a lesser risk of severe COVID-19 (OR 0.48; p = 0.02). Type of IBD was a potential factor that might have contributed to the higher level of heterogeneity. There was a significant association between ulcerative colitis and increased risk of COVID-19, COVID-19 hospitalization, and severe COVID-19 infection. This association was not observed in patients with Crohns' disease or in those diagnosed non-specifically as IBD.