Smoking, obesity-related factors significantly increase psoriasis risk

Smoking and obesity-related factors are significantly associated with an increased risk for psoriasis, according to a study.

“The risk of all-cause mortality for patients with psoriasis is 21% higher than for those without psoriasis,” Christos V. Chalitsios, MSc, PhD, of the department of hygiene and epidemiology in the School of Medicine at the University of Ioannina in Greece, and colleagues wrote. “Consequently, it is essential to understand the factors that causally affect its risk.”

Using a two-sample mendelian randomization (MR) analysis, Chalitsios and colleagues investigated the causality between several potentially modifiable factors and the risk of psoriasis. The researchers used the random-effects inverse variance-weighted (IVW) method in their statistical analysis.

The researchers evaluated risk factors from the largest genome-wide association study meta-analysis of European ancestry, including data from 19,032 cases of dermatologist-diagnosed psoriasis and 286,226 controls from eight different cohorts.

Results found that genetically predicted smoking initiation (ORMR-IVW = 1.51; 95% CI, 1.3- 1.74) and higher lifetime smoking index (ORMR-IVW = 2.11; 95% CI, 1.21-3.5) were associated with increased odds of psoriasis. Additionally, high associations with psoriasis were found for increased hip (ORMR-IVW = 1.55; 95% CI, 1.15-2.07) and waist circumference (ORMR-IVW = 1.86; 95% CI 1.31 to 2.64). Increased childhood (ORMR-IVW = 1.4; 95% CI, 1.14-1.71) and adult BMI (ORMR-IVW = 1.63; 95% CI, 1.32-2) were significantly associated with a higher risk of psoriasis as well. However, after adjusting for adult BMI in multivariable analysis, the direct effect of childhood BMI was not significant.

In contrast, higher sleep duration was associated with decreased risk of psoriasis (ORMR-IVW = 0.56; 95% CI, 0.37-0.84) as was increased years of education (ORMR-IVW = 0.78; 95% CI, 0.62-0.98), the latter persisting after adjusting for genetic predictors of smoking and adult BMI.

“The results of this study established a causal role of specific lifestyle and obesity-related factors in psoriasis risk, all of which are modifiable,” Chalitsios and colleagues wrote. “Targeting these risk factors represents an opportunity to simultaneously reduce the risk of multiple distinct disease processes and thus ease the burden of multi-morbidity on individual’s health system.”