November 13, 2023
Is microscopic colitis associated with increased risk of rheumatoid arthritis?
Microscopic colitis is associated with an increased risk of rheumatoid arthritis. Whether this reflects a common pathophysiology or increased surveillance remains to be determined.
Bergman D, Roelstraete B, Sun J, et al. Microscopic colitis and risk of incident rheumatoid arthritis: A nationwide population-based matched cohort. Aliment Pharmacol Ther. 2023;58(10):1028–1040; https://onlinelibrary.wiley.com
Prior limited research has pointed to a link between microscopic colitis (MC) and rheumatoid arthritis (RA). To shed further light on the association, Swedish researchers performed a matched cohort study using data from several national registries. Their dataset included 8,179 patients that had been diagnosed with biopsy-proven MC between 2007 and 2017 and 8,202 of their siblings without MC. A second control group included 36,400 matched individuals from the general population without MC. All study participants were prospectively followed until December 31, 2021 or until a diagnosis of RA.
The median age at MC diagnosis was 64 years of age, 71% of those with MC were female, 69% had lymphocytic colitis. The median follow-up in the overall study population was 9.1 years (Interquartile Range: 6.7–11.7 years).
Data showed 73 patients with MC and 183 of those in the general population cohort were diagnosed with RA during follow-up, translating to an incidence of 99 events per 100,000 person-years among those with MC and 55 events per 100,000 person-years in the general population. Statistical analyses confirmed an 83% higher risk of RA among those with MC (adjusted Hazard Ratio [aHR]: 1.83; 95% Confidence Interval [CI], 1.39–2.41).
Both those with MC and individuals in the general population diagnosed with RA were roughly 70 years of age at the time of diagnosis.
Compared to their siblings without MC, individuals with MC had a two-fold higher risk of RA (aHR: 2.04; 95% CI, 1.18–3.56).
The risk of RA was highest during the first year after MC diagnosis (aHR: 2.31; 95% CI, 1.08–4.97]) but remained significant up to five years following MC diagnosis (aHR: 2.16 for 1–5 years; 95% CI, 1.42–3.30).
Using budesonide prescriptions as a surrogate for disease severity, the authors found more severe MC was not associated with a further increase in the risk of RA.
Study Design: Nationwide population-based matched cohort study
Funding: The Karolinska Institutet, the Stockholm County Council, the Swedish Research Council and
the Region Stockholm/Karolinska Institutet.
Allocation: Not applicable
Setting: Single center
Level of Evidence: 1b