Obesity linked to increased risk for psoriasis regardless of age, smoking status

Researchers found that higher BMI appears to correlate with an increased risk for developing psoriasis, regardless of age, sex, race and smoking status, according to data published in the Journal of the American Academy of Dermatology.

While data on the relationship between obesity and psoriasis has been described previously, the data was mostly based on highly selected samples.

To address this limitation in the literature, Alexandra Norden, BS, of the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell in Hempstead, New York, and colleagues conducted a retrospective cohort analysis of a sample of more than 1.5 million patients in the U.S. from Jan. 1, 2008, and Sept. 9, 2019.

Their study comprised 461,236 patients with underweight or normal weight, 466,169 patients with overweight, 303,336 patients with obesity class 1 and 275,806 patients with obesity class 2/3.

Incidence of psoriasis per 100,000 person-years was 9.5 (95% CI, 9.1-10) among those patients with underweight and normal weight, 11.9 (95% CI, 11.4-12.4) among those with overweight, 14.2 (95% CI, 13.6-14.9) among those with obesity class 1, and 17.4 (95% CI, 16.6-18.2) among those with obesity class 2/3.

Patients with overweight (HR = 1.19; 95% CI, 1.12-1.27), obesity class 1 (HR = 1.43; CI, 1.34-1.53) or obesity class 2/3 (HR = 1.83; CI, 1.71-1.95) had significantly increased risks for developing psoriasis compared with patients who had a BMI less than 25 kg/m².

Additionally, the researchers concluded that a 5-unit increase in BMI correlated with a 17% (HR = 1.17; 95% CI, 1.15-1.19) increased risk for developing psoriasis.

Norden and colleagues found no evidence of a differential relationship between BMI and psoriasis based on sex, race or smoking status. However, the correlation between BMI and psoriasis weakened slightly with increasing age (interaction P = .03).

“Additional adjustments for comorbidities did not alter the main findings,” Norden and colleagues wrote. “Comorbidities may have little influence on the risk of developing psoriasis after accounting for the effects of obesity and smoking.”

The researchers noted that the potential mechanistic links between obesity and psoriasis may involve comorbid inflammatory factors.

“This analysis may support counseling efforts for patients at risk for psoriasis, such as those with a family history,” Norden and colleagues wrote. “These observations may also support mechanistic research on the relationship between obesity and psoriasis, as well as the evaluation of the role of weight loss in the management of psoriasis.”