Study Links BMI and IBD Causally to Hidradenitis Suppurativa
Key Takeaways
Genetically predicted higher BMI was associated with a 20% increased odds of hidradenitis suppurativa (HS) per BMI unit.
IBD, but not psoriasis or systemic sclerosis, were shown to have a causal relationship with HS.
Smoking showed inconsistent results across sensitivity analyses.
A new mendelian randomization (MR) analysis provides genetic evidence supporting a causal role for elevated body mass index (BMI) and inflammatory bowel disease (IBD) in hidradenitis suppurativa (HS).
Study researchers used genome-wide association study (GWAS) data from predominantly White European populations, focusing on five exposure phenotypes (BMI, smoking, psoriasis, IBD, and systemic sclerosis [SSc]) in relation to HS risk. The HS GWAS consisted of 4,814 cases and more than 1.2 million controls from Denmark, Iceland, Finland, the U.K., and the United States. The datasets included up to 1.23 million participants for smoking and approximately 700,000 for BMI.
According to genetic correlation analyses, there was significant shared heritability between HS and BMI, smoking, IBD, and psoriasis, but not SSc. Primary MR analyses showed higher genetically predicted BMI was associated with HS risk (β = 0.87), working out to a 20% increase in odds of HS per BMI unit (OR = 1.20; 95% CI, 1.17 to 1.23; P < 0.001). Smoking initially demonstrated a significant causal estimate for HS, but the association became inconsistent across sensitivity analyses and causal inference was inconclusive. Among the inflammatory comorbidities assessed, IBD was the only condition with evidence of a causal relationship with HS (β = 0.18; OR = 1.20; 95% CI, 1.15 to 1.24; P < 0.001), again without signals of pleiotropy. Psoriasis and SSc did not show causal effects in MR models despite genetic correlation.
"The findings of this study support a causal effect of increased BMI on the risk of developing HS," the authors wrote. "This information may help physicians better inform patients about disease risk contributed by modifiable lifestyle behaviors, knowledge that can be beneficial for planning subsequent lifestyle interventions." the authors wrote, “These findings indicate causal effects of IBD and increased BMI on the risk of HS,” highlighting the potential role of modifiable lifestyle factors in risk reduction strategies.
Soutrce: Andersen R, et al. JAMA Dermatology. Doi:10.1001/jamadermatol.2025.5010