Recent studies in the United Kingdom, South Korea and Denmark have found significant associations between rosacea and inflammatory bowel disease (IBD), lending further evidence to a possible connection between the two inflammatory disorders.
A Swiss research team led by Dr. Julia Spoendlin of the University of Basel conducted an analysis of data from the UK-based Clinical Practice Research Datalink, which contains health information for approximately 11 million people. The researchers identified 80,957 individuals who had been diagnosed with subtype 1 (erythematotelangiectatic) or subtype 2 (papulopustular) rosacea between 1995 and 2013, and matched them with an equal number of people who did not have rosacea. They then looked for patients in both groups who had been diagnosed with ulcerative colitis or Crohn's disease -- the two most common forms of IBD -- or unspecified IBD.
The overall incidence of IBD was small, with only 992 (1.2 percent) of the rosacea group and 625 (0.8 percent) of the control group receiving such diagnoses during the study period. However, within this small group, patients with ulcerative colitis were 65 percent more likely to have rosacea, and patients with Crohn's disease were 49 percent more likely to have rosacea. The investigators reported that the risk for rosacea grew with the increased severity of IBD symptoms. In addition, treatment of gastrointestinal symptoms with steroid medications more than doubled the likelihood a patient with Crohn's disease would have rosacea, and more than tripled the likelihood for ulcerative colitis patients.
Dr. Miri Kim and colleagues from the Catholic University of Korea and Dr. Kwang Hyun Choi of the Veterans Health Service Medical Center conducted a nationwide cross-sectional study using data from the Korean National Health Insurance database, which includes 97.2 percent of the population. The investigators approached their study from the IBD side, identifying 40,843 patients diagnosed between 2009 to 2013 with Crohn's disease or ulcerative colitis, as well as a control group of 122,529 people without IBD, and tracking the diagnosis of concurrent inflammatory skin diseases such as rosacea, psoriasis and atopic dermatitis and concurrent autoimmune skin diseases like vitiligo and alopecia areata.
The results showed a general association between IBD and the inflammatory skin diseases tested, but no significant connection between IBD and the autoimmune skin diseases. The researchers reported that a diagnosis of rosacea in patients with IBD was more than twice as likely than in healthy patients. Psoriasis was 78 percent more common in IBD patients, and atopic dermatitis was 37 percent more common.
Men with IBD were found to be at a higher risk for rosacea than women, while the opposite was true for psoriasis. Interestingly, while rosacea tends to affect more people as they get older, the researchers found that IBD patients under 30 were more likely to be diagnosed with rosacea than older patients in the study.
As reported earlier this year, a Danish study analyzing that country's national registry system found that rosacea patients were more likely to have both types of IBD, with a 45 percent greater risk of Crohn’s disease and a 19 percent heightened risk of ulcerative colitis.
Though all three studies show an association between the diseases, the nature of the relationship remains unclear. Dr. Spoendlin's team noted in its report that both IBD and rosacea are believed to be inflammatory diseases involving the surface of the skin or lining of the colon, and both involve an innate immune system reaction. The Korean researchers also noted the innate immune system connection, in particular the involvement of cathelicidins, an antimicrobial molecule that has been studied as a potential cause of rosacea's inflammatory bumps and pimples. All three research groups recommended further study to determine the nature of the connection between the disorders.
The occurrence of two disorders or illnesses in the same person, at the same time or one after another, is called "comorbidity." A positive association between two medical conditions does not necessarily mean that one causes the other. Diseases that show an association may share a common pattern of influences or be due to the resilience or vulnerability of the individual. Other possible explanations may be that risk factors for the individual diseases may make them more likely to appear together, or simple chance. Studies of comorbidity may provide pointers to the patterns and causes of diseases, and awareness of comorbidity may help health care providers assess the burden of disease – the impact of the disorders taken in context with the individual’s life situation – for the benefit of patients as well as health service planning.
There were limitations reported in each of the studies. In the UK study, patients with ocular rosacea and rhinophyma were excluded, the study was not controlled for medication use, and the number of rosacea and IBD cases may be inaccurate due to lack of diagnosis or misdiagnosis. In the Korean study, neither subtypes or severity of rosacea nor environmental or lifestyle factors were considered, and because rosacea is not covered by insurance in South Korea, the number of cases may be misrepresented. In the Danish study, the data did not distinguish between rosacea subtypes, and because of the homogeneity of the Danish population, the results may not be extrapolated for patients of other ethnicities.
1. Spoendlin J, Karatas G, Furlano RI, et al. Rosacea in patients with ulcerative colitis and Crohn's disease: a population-based case-control study. Inflammatory Bowel Disease. 2016 March;22(3):680-7.
2. 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. Journal of the American Academy of Dermatology. 2016 Oct 25. doi: 10.1016/j.jaad.2016.08.022. [Epub ahead of print]
3. Egeberg A, Weinstock LB, Thyssen EP, et al. Rosacea and gastrointestinal disorders: a population-based cohort study. British Journal of Dermatology. 2016 Aug 8. doi: 10.1111/bjd.14930. [Epub ahead of print]