For the first time, a new study from China shows that the presence of inflammatory bowel disease (IBD), a well-known comorbidity of rosacea, as well as its subtypes, Crohn’s disease (CD) and ulcerative colitis (UC), may lead to rosacea, according to the report published in the scientific journal Nature Scientific Reports.¹  

“Our findings provided evidence for a causal impact of IBD, UC and CD on rosacea, but not vice versa,” the investigators wrote. “The elevated incidence of rosacea in patients with IBD should be recognized by doctors to make an early diagnosis and initiate specialized therapy.”

Comorbidity alone – the occurrence of two disorders in the same person – does not necessarily mean that one causes the other, though these associations are notable because they provide potential helpful indicators such as the patterns and causes of each, for example, or to risk factors that may make them likely to appear together. Rosacea has been linked to a wide range of comorbidities, including a growing number of potentially life-threatening systemic illnesses, and IBD and its subtypes in particular have recently been shown to often appear alongside rosacea, though sometimes with conflicting interpretations.^2-4

The study used data from the FinnGen Consortium project, which collected biological samples from 500,000 participants in Finland with the aim of improving health through genetic research. The investigators in the new study were able to isolate genetic characteristics from rosacea and IBD only but avoided complicating variables for both disorders, such as cardiometabolic disease, Helicobacter pylori, Demodex infection, migraine, depression, anxiety and obesity.

Using reverse-direction Mendelian randomization, a statistical genetic analysis method, they found evidence that a genetic predisposition to IBD, UC and CD was linked to an elevated risk for rosacea. The reverse was not true, however; there was no evidence that genetic predisposition to rosacea raised a patient’s risk for IBD, UC or CD, they said.

While the results may clarify the causal relationship between rosacea and IBD, the underlying mechanisms of that link have not yet been fully elucidated, the researchers noted. The two disorders share many factors: both are chronic inflammatory conditions involving the interplay between genetic and immunological elements; both have abnormalities in innate and adaptive immunity; and they share some common risk factors such as smoking, obesity and small intestinal bacterial overgrowth (SIBO). Moreover, the investigators observed that certain medications used to treat IBD, such as topical or systemic corticosteroids, have been reported in the literature to be associated with rosacea’s onset, and noted that medication-induced symptoms of rosacea often resolve after discontinuation of the triggering medication.

More research is required to further understand the pathophysiological processes behind this association, the investigators said.

References

1. Li M, He SX, He YX, Hu XH, Zhou Z. Detecting potential causal relationship between inflammatory bowel disease and rosacea using bi-directional Mendelian randomization. Nature Sci Rep 2023;Sep 9;13(1):14910.

2. Spoendlin J, Karatas G, Furlano RI, et al. Rosacea in patients with ulcerative colitis and Crohn’s disease: a population-based case-control study. Inflamm Bowel Dis 2016;22(3):680–687.

3. Kim M, Choi KH, Hwang SW, et al. Inflammatory bowel disease is associated with an increased risk of inflammatory skin diseases: a population-based cross-sectional study. J Am Acad Dermatol 2016 Oct 25. doi: 10.1016/j.jaad.2016.08.022. [Epub ahead of print]

4. Egeberg A, Weinstock LB, Thyssen EP, et al. Rosacea and gastrointestinal disorders: a population based cohort study. Br J Dermatol 2016 Aug 8. doi: 10.1111/bjd.14930.