Patients with rosacea had an increased risk of subsequently developing irritable bowel syndrome (IBS), while patients with IBS also had an elevated risk of developing rosacea, a cohort study found. The findings support the proposed relationship between gastrointestinal and cutaneous inflammation.
Investigators conducted the retrospective population-based study using the Korean National Health Insurance Service–National Sample Cohort, examining 712,331 adults aged 20 years or older from 2002 to 2013. The analysis compared 1,085 patients with rosacea with 4,340 matched controls and 244,156 patients with IBS with 244,156 matched controls. Participants were matched by age, sex, and index year. Cox proportional hazards models accounted for sociodemographic characteristics and comorbidities, and medication exposures were assessed in sensitivity analyses.
The investigators evaluated 2 primary outcomes: the incidence of IBS following a rosacea diagnosis and the incidence of rosacea following an IBS diagnosis. Additional analyses assessed sex-based associations and examined the influence of medication exposure, including isotretinoin, doxycycline, and minocycline.
During a median follow-up of 6.25 years, IBS incidence was 56.3 per 1,000 person-years among patients with rosacea compared with 36.9 per 1,000 person-years among matched controls. Following adjustment for sociodemographic factors and comorbidities, patients with rosacea had a 30% higher hazard of subsequently developing IBS.
In the reverse analysis, during a median follow-up of 6.24 years, rosacea incidence was 0.37 per 1,000 person-years among patients with IBS compared with 0.21 per 1,000 person-years among controls. Patients with IBS had a 61% higher adjusted hazard of subsequently developing rosacea. Although the relative association was greater in this direction, the absolute incidence of rosacea remained low.
Men with rosacea had a 52% higher adjusted hazard of developing IBS compared with matched controls, whereas the association among women was not statistically significant. Conversely, men with IBS had approximately twice the adjusted hazard of subsequently developing rosacea, while women with IBS had a 41% higher adjusted hazard.
The bidirectional associations persisted across sensitivity analyses, including models adjusting for isotretinoin, doxycycline, and minocycline exposure. However, the risk estimates were somewhat attenuated following medication adjustment. The researchers suggested that medication exposure might partly explain the associations, although the observational analysis could not establish a treatment-related effect.
The investigators proposed that shared microbial, inflammatory, and neuroimmune mechanisms could underlie the relationship between rosacea and IBS. Both conditions have been associated with alterations in gut microbiota, low-grade systemic inflammation, epithelial barrier dysfunction, and neurovascular dysregulation. These overlapping pathways may contribute to communication between the gastrointestinal tract and skin through the gut–skin axis, although the study did not directly evaluate these mechanisms.
The study had several limitations. Diagnoses were identified through administrative codes without information on disease severity, and the database lacked information on diet, stress, and microbiome composition. Patients with either condition may also have had more frequent health care encounters, increasing the likelihood of receiving an additional diagnosis and potentially inflating the observed associations. Excluding patients diagnosed during the initial study year may have introduced selection bias, while the absence of IBS subtype analyses limited subgroup interpretation. The observational design also prevented causal conclusions.
The findings provided epidemiologic evidence of a reciprocal association between rosacea and IBS, although the authors emphasized the need for further mechanistic and longitudinal investigations to clarify the relationship.
“Physicians managing either condition should be aware of the potential coexistence of the other,” wrote co-first authors Joon-hong Min, MD, of the Department of Dermatology, and Young Woo Jo, PhD, of the Department of Medical Statistics, at Kangwon National University School of Medicine, and colleagues.
The authors reported no conflicts of interest. The study received funding from Kangwon National University, the Korea Health Technology R&D Project, and Kangwon National University Hospital.
Source: Annals of Dermatology
