Inflammatory bowel disease and risk of severe COVID-19: A nationwide population-based cohort study in Sweden

Background There are concerns that individuals with chronic immune-mediated diseases are at increased risk of COVID-19 and related severe adverse outcome, including intensive care admission or death. We aimed to explore the absolute and relative risk of severe COVID-19 in inflammatory bowel disease (IBD). Methods This population-based cohort study used nationwide registers in Sweden, with 67,292 individuals with a diagnosis of IBD 1969-2017 (Crohn's disease, n = 21,599; ulcerative colitis: n = 43,622; IBD-unclassified: n = 2071) and alive on 1 February 2020. Patients with IBD were matched to up to five controls from the general population (n = 297,910). Cox regression estimated hazard ratios (HRs) for (i) hospital admission with laboratory-confirmed COVID-19 as the primary diagnosis, and (ii) severe COVID-19 (composite outcome consisting of (a) COVID-19 intensive care admission, or (b) death from COVID-19 or (c) death within 30 days of COVID-19 hospital admission), were calculated. Analyses were conditioned on age, sex, calendar period, and county and adjusted for other comorbidities. Results Between 1 February and 31 July 2020, 179 (0.27%) IBD patients and 500 (0.17%) general population controls were admitted to hospital with COVID-19 (adjusted HR [aHR] = 1.43; 95% CI = 1.19-1.72). The corresponding numbers for severe COVID-19 was 65 (0.10%) and 183 (0.06%; aHR = 1.11; 95% CI = 0.81-1.52). Adjusted HRs were similar in Crohn's disease and ulcerative colitis. In a propensity score-matched model taking comorbidity into account until 2016, the increased risk for COVID-19 hospital admission remained (aHR = 1.32; 1.12-1.56), but there was no increased risk of severe COVID-19 (aHR = 1.12; 0.85-1.47). Conclusions While individuals with IBD were more likely to be admitted to hospital for COVID-19 than the general population, the risk of severe COVID-19 was not higher.