Inflammatory Bowel Disease and BMI Increase Risk of Hidradenitis Suppurativa: JAMA
A new study published in the Journal of American Medical Association showed that higher body mass index (BMI) and an increased incidence of hidradenitis suppurativa (HS) were found to be causally related to inflammatory bowel disease (IBD)
Hidradenitis suppurativa is linked to obesity and smoking, both of which are significant environmental risk factors. This study examined the relationship between smoking and HS and BMI. The secondary aim was to look into possible connections between HS and three inflammatory diseases: psoriasis, IBD, and systemic sclerosis (SSc).
In 2024, a Mendelian randomization (MR) research was carried out on the impact of five exposure phenotypes (BMI, smoking, psoriasis, IBD, and SSc) on the result of phenotypic HS. Large genetic White European cohorts from genome-wide association studies (GWAS) of each of the six traits were employed in the MR analysis. May 2024 saw the completion of preliminary assessments, which were revised in May 2025. Predetermined genome-wide significant single-nucleotide variations are used as proxy for each of the five exposure phenotypes.
4,814 cases and more than 1.2 million controls from Iceland, Denmark, Finland, the UK, and the US made up the GWAS of hidradenitis suppurativa. About 700,000 people from the UK Biobank and the GIANT group participated in the BMI GWAS, while 1.23 million people from an international consortia provided genetic data related to smoking.
Using information from a commercial genetic testing firm, the psoriasis GWAS assessed 286,769 controls and 39,498 patients of White European ancestry. The International IBD Genetics Consortium provided 38,155 patients and 48,485 controls for the IBD meta-analysis, whereas White European populations provided 9,095 cases and 17,584 controls for the SSc GWAS.
With the exception of SSc, genetic correlation analysis revealed strong relationships between HS and every exposure. BMI and IBD were found to have a causative influence in HS risk, with no indication of pleiotropy, according to Mendelian randomization; smoking, on the other hand, had an initial causal signal that diminished during sensitivity testing. Overall, this study showed that IBD and elevated BMI have a causal relationship with the risk of HS.
Source:
Kjærsgaard Andersen, R., Riis, P. T., Zachariae, C., Thomsen, S. F., Quin, L., Dinh, K. M., Banasik, K., Brunak, S., Hansen, T., Hjalgrim, H., Sørensen, E., Mikkelsen, C., Ullum, H., Nyegaard, M., Bruun, M. T., Erikstrup, C., Ostrowski, S. R., Eidsmo, L., Lindhardt Saunte, D. M., … Jemec, G. B. E. (2025). Hidradenitis suppurativa and smoking, obesity, psoriasis, inflammatory bowel disease, and systemic sclerosis: Results from A 2-sample Mendelian randomization study: Results from A 2-sample Mendelian randomization study. JAMA Dermatology (Chicago, Ill.). https://doi.org/10.1001/jamadermatol.2025.5010
