Letter: association between COVID-19 and inflammatory bowel disease.

Editors,

We read with great intriguing the research TriNetX network analysis by Yousaf Hadi et al. They described a decreased risk of COVID‐19 infection in the IBD patients with incidence rate ratio of 0.79; another breakthrough was about no increased risk for new‐onset IBD after COVID‐19 infection. This research has produced valuable results. However, we believe that some methodological issues should be considered that would add strength to the article.

First, because the authors selected IBD cases by ICD‐10 codes plus IBD therapeutic drugs, we suggest specific procedures such as endoscopy with biopsy should be included to avoid selection bias. Since ICD‐10 codes for COVID‐19 change and update during the pandemic, we would like the authors to describe the exact codes they used rather than gloss over, so that other researchers can replicate them afterwards.

Second, patients with immune‐mediated inflammatory diseases are encouraged to receive the SARS‐CoV‐2 vaccine. We recommend that the authors take into account individual vaccine status to make their report more closely related to real‐world practice. ,

Third, the authors had included anti‐TNF, biologics and steroids in their analysis, but should consider including antibiotics in their adjustment when investigating the risk of IBD after COVID‐19 infection, because antibiotics play important role in the development of IBD. ,

Although a causal and definitive effect of COVID‐19 on IBD will require future studies to reach a final conclusion, we thank Yousaf Hadi et al. for their excellent article and look forward to their response.