Obesity and IBD Drive Hidradenitis Suppurativa Risk
HIDRADENITIS suppurativa (HS) is a chronic, painful skin disease with substantial impact on quality of life. While clinical observations have long suggested links between lifestyle factors and HS, new genetic research confirms that certain factors directly contribute to disease development. A recent Mendelian randomisation (MR) study involving over 3.5 million individuals has revealed causal relationships between BMI, inflammatory bowel disease (IBD), and HS.
Understanding Hidradenitis Suppurativa and Genetic Risk
HS is influenced by both genetic and environmental factors, with obesity and smoking historically identified as key environmental contributors. However, disentangling correlation from causation has been challenging. The MR approach leverages genetic variants as natural proxies for exposures, offering a powerful method to infer causal effects. In this study, researchers examined five exposures (BMI, smoking, psoriasis, IBD, and systemic sclerosis) using large genome-wide association study (GWAS) cohorts across Europe and North America.
Key Findings on Lifestyle and Inflammatory Conditions
The study found a robust causal effect of increased BMI on HS, with each unit rise in BMI increasing the odds of HS by approximately 20% (OR 1.20, 95% CI 1.17–1.23, P < .001). This confirms long-standing clinical impressions that obesity is not merely associated with HS, but actively contributes to disease risk. Smoking initially appeared to increase HS susceptibility, but sensitivity analyses rendered this effect inconclusive, suggesting additional research is needed to clarify its role.
Notably, IBD was also identified as a causal risk factor for HS (OR 1.20, 95% CI 1.15–1.24, P < .001), highlighting the systemic interplay between gastrointestinal inflammation and skin disease. In contrast, results for psoriasis and systemic sclerosis did not support a direct causal relationship, indicating that not all inflammatory conditions equally predispose individuals to HS.
Moving Towards Targeted Interventions
By confirming causal links, this research encourages a proactive approach in HS prevention and early intervention. Patients with obesity or IBD may benefit from tailored counselling and multidisciplinary care, potentially reducing disease onset or severity. Further studies are needed to clarify smoking’s role and explore whether targeted interventions can mitigate HS risk.
This landmark study reinforces the importance of lifestyle modification and systemic disease management in HS, equipping dermatologists with actionable insights for improving patient outcomes.
Reference
Kjærsgaard Andersen R et al. Hidradenitis Suppurativa and Smoking, Obesity, Psoriasis, Inflammatory Bowel Disease, and Systemic Sclerosis: Results From A 2-Sample Mendelian Randomization Study. JAMA Dermatol. 2025; DOI:10.1001/jamadermatol.2025.5010.
