Obesity, waist circumference, weight change and risk of incident psoriasis: prospective data from the HUNT Study.

Snekvik, I. ; Smith, C.H. ; Nilsen, T.I.L. ; Langan, S.M. ; Modalsli, E.H. ; Romundstad, P.R. ; Saunes, M. ;
Obesity, waist circumference, weight change and risk of incident psoriasis: prospective data from the HUNT Study.
J Invest Dermatol, 2017;

Although psoriasis has been associated with obesity, there are few prospective studies with objective measures. We prospectively examined the effect of body mass index (BMI), waist circumference, waist-hip ratio (WHR) and 10-years weight change on the risk of developing psoriasis among 33,734 people in the population-based HUNT Study, Norway. During follow-up, 369 incident psoriasis cases occurred. Relative risk (RR) of psoriasis was estimated from Cox regression. One standard deviation (SD) higher BMI, waist circumference and WHR gave RRs of 1.22 (95% confidence interval (CI) 1.11-1.34), 1.26 (95% CI 1.15-1.39), and 1.18 (95% CI 1.07-1.31), respectively. Compared to normal weight, obese people had a RR of 1.87 (95% CI 1.38-2.52) whereas comparing 4(th) to 1(st) quarter of waist circumference gave a RR of 1.95 (95% CI 1.46-2.61). One SD higher weight change gave a RR of 1.20 (95% CI 1.07-1.35), and people who increased their body weight by ≥10 kg had a RR of 1.72 (95% CI 1.15-2.58) compared to being weight stable. In conclusion, obesity and high abdominal fat mass doubles the risk of psoriasis, and long term weight gain substantially increases psoriasis risk. Preventing weight gain and promoting maintenance of a normal body weight could reduce incidence of psoriasis.