Inflammatory Bowel Disease and the SARS-CoV-2 Pandemic: More Speed, Less Haste

Dear Editors:

The ongoing severe acute respiratory syndrome novel coronavirus 2 (SARS-CoV-2) pandemic is one of the greatest medical challenges of the modern era. This emergency raises several questions for patients with chronic diseases, including inflammatory bowel disease (IBD). Do patients with IBD present a higher risk of infection with SARS-CoV-2? Do immunosuppressive drugs have an impact on the risk of complications and/or death after developing novel coronavirus disease 2019 (COVID-19)? At present, no evidence-based guidelines have been issued in this respect, and so gastroenterologists are unable to advise and reassure their patients. In contrast, it is possible that immunosuppressants might dampen the cytokine storm associated with severe COVID-19.

A recent publication in Gastroenterology reported on a cohort of patients with IBD in at the university hospital in Bergamo, Italy. Over a 1-month period, none of the 522 monitored patients developed COVID-19.¹ Similarly, no cases of COVID-19 had been observed in an IBD cohort in Wuhan, China, 2 months after the start of the local SARS-CoV-2 outbreak ². The researchers concluded—hastily, in our opinion—that IBD patients taking immunosuppressants might have a lower risk of developing COVID-19.

The provision of well-grounded answers to these questions requires complex epidemiologic risk and benefit analyses with an a priori sample size calculation and a design that takes account of confounding factors and likely sources of bias.³ According to modelling results recently published by the Institut Pasteur (Paris, France), only 6% of the French population may have been in contact with SARS-CoV-2, and 2.6% of exposed people have been hospitalized for COVID-19.⁴ Given the lack of solid epidemiologic evidence, we referred to our population-based registry (EPIMAD) of all incident cases of IBD recorded in northern France since 1988.⁵ This area has around 6 million inhabitants, or approximately 10% of the whole French population. We calculate that at the time of writing, approximately 20 patients with IBD should have been hospitalized for COVID-19 in northern France. We also hypothesize that a lower than expected number of severe cases of COVID-19 might be primarily owing to tighter containment of people suffering from chronic diseases.

This low expected number of incident cases of COVID-19 among patients with IBD prevents any analysis of factors associated with severe viral disease. Our calculation highlights how difficult is it to build rigorous, robust studies designed to answer crucial questions about managing patients with chronic diseases during the SARS-CoV-2 pandemic.

The recently published, underpowered publications cannot provide answers for patients with IBD, and more generally infrequent diseases, and may even prompt misguided and possibly harmful treatment decisions.