— The relationship was particularly pronounced in women

by Kate Kneisel, Contributing Writer, MedPage Today
May 28, 2025 • 4 min read

Among 25 different measures of adiposity, abdominal fat was significantly associated with a risk for psoriasis, particularly among women, a cross-sectional study suggested.

Using data on 336,806 participants in the U.K. Biobank of white British ancestry, including 9,305 with psoriasis, four measures of central adiposity had the largest effect size for an association with psoriasis: waist-to-hip ratio (OR 1.26, P<0.00001), abdominal fat ratio (OR 1.24, P<0.00001), total abdominal adipose tissue index (OR 1.22, P<0.00001), and waist circumference (OR 1.23, P<0.00001), reported Catherine Smith, MD, of St John’s Institute of Dermatology at King’s College London, and colleagues in the Journal of Investigative Dermatology.

“The relationship between central adiposity and psoriasis was particularly pronounced in females, with larger effect sizes observed across several measures compared with those in males,” the group noted. For instance, visceral adipose tissue mass had a stronger association in women (interaction with sex P=0.0067).

“Our research shows that where fat is stored in the body matters when it comes to psoriasis risk. Central fat — especially around the waist — seems to play a key role,” said co-author Ravi Ramessur, MBBS, also of King’s College London, in a statement. “The observed links between central body fat and psoriasis suggest that there may be underlying biological mechanisms contributing to the disease that are not yet fully understood and which warrant further investigation.”

Interaction analyses to identify potential associations between adiposity measures and psoriasis polygenic risk scores (both including and excluding HLA-C*06:02) showed that full psoriasis polygenic risk scores were significantly associated with waist-to-hip ratio (P=0.047).

However, the interaction effect was no longer significant when HLA-C*06:02 was excluded from the polygenic risk score (P=0.141), “suggesting that the presence of HLA-C*06:02 has a major contribution to the significant interaction effect observed with the full psoriasis polygenic risk score,” Smith and team explained.

“In line with these findings, waist-to-hip ratio was associated with psoriasis with a significantly larger effect size in HLA-C*06:02-negative versus HLA-C*06:02-positive participants … consistent with previous observations,” they added.

Conversely, full psoriasis polygenic risk score with percentage body fat was not significantly linked with psoriasis risk (P=0.314), which the authors noted “may reflect differences in measurement precision rather than differences in biological relevance of central adiposity in psoriasis risk.”

“These findings have important translational implications for both clinical practice and public health,” they concluded. “The strong association between central adiposity and psoriasis, independent of genetic risk, suggests that waist-to-hip ratio could serve as a useful marker for identifying individuals at higher risk of psoriasis, including those at risk of more severe disease.”