key: cord-0788571-37p81g3z
authors: Taxonera, Carlos; Alba, Cristina; Olivares, David
title: What is the incidence of COVID-19 in patients with IBD in western countries?
date: 2020-07-17
journal: Gastroenterology
DOI: 10.1053/j.gastro.2020.05.099
sha: ab27935d2b09dde7d7ca7b904f39284317a5c8f1
doc_id: 788571
cord_uid: 37p81g3z

nan

Letter to the editor:

Carlos Taxonera 1 Author contributions: CT wrote the letter, CA and DO performed statistical analysis and contributed with critical revision.

We read with interest the article by Gubatan et al [1] reporting that, among 168 IBD patients tested in Northern California (Stanford University School of Medicine), the prevalence of COVID-19 was 3.0%, comparable with the population-weighted prevalence of SARS-CoV-2 positive serology in Santa Clara County at 2.8%. The authors concluded that their results provided much needed epidemiological data and reassurance that COVID-19 rates in IBD patients may be comparable to the general population.

Data on COVID-19 incidence in IBD have been contradictory. Initial evidence from China suggested that IBD patients even had a decreased risk of COVID-19 compared with the general population, since no patients with IBD were reported to be infected with SARS-CoV-2 in the IBD Elite Union, which covers the seven largest IBD referral centers in China, or in the 3 largest tertiary IBD centers in Wuhan. [2] Subsequently, a study reported that among 522 IBD patients followed in a tertiary center at Bergamo, the Italian province with one of the highest rates of infection anywhere in the world, no case of COVID-19 was diagnosed. [3] We recently evaluated the risk of COVID-19 and associated mortality among unpublished data]. After adjusting for age we obtained an age-standardized rate of 4.9 COVID-19 cases per 1000 IBD patients, which was slightly lower than the rate in the general population. Given the low number of COVID-19 cases in our series, any missed diagnoses would, however, have a high impact on the reported incidence rate. We also reported an age-adjusted COVID-19 associated mortality rate of 0.82 per 1000 IBD patients, similar to that of the general population.

A third study assessed the incidence of COVID-19 among a cohort of IBD patients from France (Nancy University Hospital; 2000 patients) and Italy (Humanitas, Milan; 4000 patients). [5] They identified 15 COVID-19 cases, corresponding to a crude cumulative incidence of 2.5 cases per 1000 IBD patients, which was considered broadly similar to that observed in the general population (the cumulative incidence in France and Italy was 1.7 cases per 1000 at the time of the study). Incidence was not adjusted by age, and we do not know if the mean age of the IBD cohort was higher than that of the general population. If this were so, it would be expected that the agestandardized rate of COVID-19 in IBD would be less than that reported. We believe this study could also be affected by underreporting of COVID-19 among the IBD population, while all positive viral RT-PCR were counted for the general population.

Although available evidence is limited, it seems that IBD patients are not at a greater risk of acquiring COVID-19. This is noteworthy since around 37% of IBD patients in the Northern California cohort and our cohort in Madrid were receiving immunosuppressants and/or biologics. [1, 5] The impact of these drugs on SARS-CoV-2 infection acquisition or progression needs to be further investigated. While thiopurines [6] and anti-TNF [7] have been associated with serious viral infections, some authors believe that IBD patients might be protected against severe disease because the viralinduced 'cytokine release storm' sometimes reported in COVID-19 could potentially be attenuated by the potent anti-inflammatory drugs commonly used to treat IBD. As a result, COVID-19 may be milder in these patients and so infection may not be confirmed by testing. In agreement, a recent study of patients included in the SECURE-IBD registry reported that TNF antagonist monotherapy was not associated with and even may have a protective effect against severe COVID-19. [8] We also believe that rigorous adherence of IBD patients to protective measures, encouraged by routine advice from IBD nurses and IBD staff, may further help contain SARS-CoV-2 dissemination in this population.

In conclusion, we agree with Gubatan et al [1] that available data indicate that COVID-19 is not more prevalent in patients with IBD than in the general population.

United Eur

Online ahead of print