Pediatric Psoriasis and Excess and Central Adiposity

The incidence of psoriasis in children has more than doubled since the early 1970s. The immune-mediated inflammatory skin disease affects 2.5% to 3.5% of the population worldwide and begins during childhood, particularly during adolescence, in 22% to 33% of cases. It is known that adults with psoriasis are at increased risk for obesity, myocardial infarction, stroke, and diabetes mellitus.

Recent studies have shown an association between psoriasis and obesity in children. Researchers recently conducted a multi-center, cross-sectional study designed to assess the relationship of excess and central adiposity with severity of pediatric psoriasis. They reported results of the study in JAMA Dermatology [2013;149(2):166-176].

The goals of the study were to (1) evaluate the effect of disease severity on the association of psoriasis with excess adiposity; (2) assess whether central obesity, as a surrogate for higher cardiovascular risk, was related to severity of psoriasis; and (3) examine whether the association of excess adiposity with psoriasis varied regionally. The researchers hypothesized that “excess adiposity and central adiposity are most highly correlated with psoriasis of greater severity, but that children with mild psoriasis are also at risk.” It was also expected that children with psoriasis in the United States would be at greater risk of excess and central adiposity than psoriatic children in other countries.

The primary outcome measures were excess adiposity (body mass index [BMI] percentile) and central adiposity (waist circumference percentile and weight to height ratio). Excess adiposity was defined as BMI ≥85th percentile. Obesity was defined as BMI ≥95th percentile.

The study enrolled 614 children from 9 countries. Of those, 33.1% (n=203) had moderate psoriasis (MP) and 33.6% (n=206) had severe psoriasis (SP) based on assessment of peak severity. The study also included 205 age- and sex-comparable children without inflammatory disorders as a control group.

Excess adiposity occurred in 155 (37.9%) of the children with psoriasis compared with 42 (20.5%) of the children in the control group; obesity occurred in 20.2% of children with psoriasis compared with 7.3% of controls (P<.001 for both comparisons).The odds ratio (OR) for excess adiposity in children with psoriasis of all severities versus controls was 2.65 (95% confidence interval [CI], 1.70-4.15). The OR for excess adiposity did not differ by severity of psoriasis.

The OR for obesity overall in psoriatic children versus controls was 4.29 (95% CI, 1.96-9.39).

The OR for obesity was higher with severe (4.92; 95% CI, 2.20-10.99) than with mild (3.60; 95% CI, 1.56-8.30). This difference was particularly evident in the United States (7.60 [95% CI, 2.47-23.34], and 4.72 [95% CI, 1.43-15.56], respectively).

Among all study participants, waist circumference above the 90th percentile occurred in 19 (9.3%) of the control group, 27 (14.0%) of the group with MP, and 43 (21.2%) of the group with SP; in the United States, the incidence was 12.0% (n=13), 20.8% (n=16), and 31.3% (n=32), respectively.

Waist to height ratio was significantly higher in the psoriasis group (0.48) compared with the control group (0.46); there was no difference associated with severity of psoriasis. Among children with SP at enrollment whose disease progressed to MP during the study period, there was no significant difference in excess or central adiposity compared with children whose psoriasis remained severe.

In conclusion, the researchers said, “Globally, children with psoriasis have excess adiposity and increased central adiposity regardless of psoriasis severity. The increased metabolic risks associated with excess and central adiposity warrant early monitoring and lifestyle modification.”