Association of Pediatric Psoriasis Severity With Excess and Central Adiposity

Abstract

Psoriasis is an immune-mediated inflammatory skin disease that affects 2.5% to 3.2% of the global population.^1,2 Psoriasis begins during childhood in 22% to 33% of the cases, especially during adolescence,^2-5 and the incidence in children has more than doubled since the early 1970s.³ Adults with psoriasis have an increased risk of obesity, myocardial infarction, stroke, and diabetes mellitus.^6-9 Recent studies also suggest the association of psoriasis with obesity in children. Of 211 North American children with moderate to severe psoriasis in an etanercept trial, 37% were obese (body mass index [BMI] ≥95th percentile).¹⁰ Among 96 Italian children with mild to severe psoriasis, 48% were overweight (BMI ≥85th percentile) vs 27% of controls.¹¹ Using a German pediatric registry, obesity (by International Classification of Diseases, 10th Revision [ICD-10 ] code) occurred 1.7-fold more often in psoriatic children than controls.⁵ In a US-based registry, overweight, moderately obese, and extremely obese children had 1.31-, 1.39-, and 1.78-fold greater odds, respectively, of having psoriasis (by International Classification of Diseases, Ninth Revision [ICD-9 ] code) than did children with normal weight.¹² These investigations provide evidence that children with psoriasis are at increased risk of being overweight or obese. However, ascertainment bias and underidentification are limitations of registry studies, which rely on ICD codes for diagnosis of psoriasis and obesity rather than direct examination and measurements to calculate BMI. In addition, the risk of excess adiposity relative to psoriasis severity has received little attention. Increased waist circumference (WC) percentile^13-16 and waist to height ratio^15-20 are noninvasive surrogates for determination of central adiposity and more sensitive indicators for metabolic disease than is BMI percentile, including in children.^15,16,19,20 Waist circumference percentile is increased in adults with psoriasis²¹ but has never been assessed in psoriatic children. Waist to height ratio has more recently been found to be a better predictor of cardiovascular risk than BMI or WC percentiles^17,19 but has never been assessed in adult or pediatric patients with psoriasis.