Inflammatory Bowel Disease and Parkinson’s Disease: A Nationwide Swedish Cohort Study

Background: Few studies have examined the association between inflammatory bowel disease (IBD) and Parkinson's disease (PD). Methods: To estimate the incidence and relative risk of PD development in a cohort of adult IBD, we included all incident IBD patients (n = 39, 652) in the Swedish National Patient Register (NPR) between 2002 and 2014 (ulcerative colitis UC: n = 24, 422; Crohn's disease CD: n = 11, 418; IBD-unclassified IBD-U: n = 3812). Each IBD patient was matched for sex, age, year, and place of residence with up to 10 reference individuals (n = 396, 520). In a cohort design, all incident PD occurring after the index date was included from the NPR. In a case-control design, all incident PD occurring before the index date was included. The association between IBD and PD and vice versa was investigated by multivariable Cox and logistic regression. Results: In IBD, there were 103 cases of incident PD, resulting in hazard ratios (HRs) for PD of 1. 3 (95% confidence interval CI, 1. 0-1. 7; P = 0. 04) in UC, 1. 1 (95% CI, 0. 7-1. 7) in CD, and 1. 7 (95% CI, 0. 8-3. 0) in IBD-U. However, these effects disappeared when adjusting for number of medical visits during follow-up to minimize potential surveillance bias. In a case-control analysis, IBD patients were more likely to have prevalent PD at the time of IBD diagnosis than matched controls, with odds ratios of 1. 4 (95% CI, 1. 2-1. 8) in all IBD patients, 1. 4 (95% CI, 1. 1-1. 9) for UC, and 1. 6 (95% CI, 1. 1-2. 3) for CD patients alone. Conclusions: IBD is associated with an increased risk of PD, but some of this association might be explained by surveillance bias. 10. 1093/ibd/izy190ᵥideo1izy190. video15785623138001.