MILWAUKEE – Excess adiposity occurred prior to psoriasis in 93% of 29 overweight and obese psoriatic children, in a chart review examining the relationship between psoriasis and obesity.
Further, 78% of patients were obese before developing psoriasis, Dr. Lauren Becker reported at the annual meeting of the Society for Pediatric Dermatology.
Although the authors anticipated that most of the children would show increased adiposity before psoriasis based on clinical observations, "none of us predicted that it would be 27 of 29," she said in an interview. "It really was incredible, and even the ones who were normal weight became overweight or obese within a year of their psoriasis."
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Dr. Lauren Becker
The review was sparked by a recent international study, led by senior author Dr. Amy Paller of Northwestern University in Chicago, in which 38% of psoriatic children had excess central adiposity (high waist-to-height ratio) compared with 21% of controls. The odds of obesity were also several times higher than those reported for adults with psoriasis, jumping 4.29-fold overall in psoriatic children versus controls, 4.92-fold in those with severe versus mild psoriasis, and 7.6-fold in the United States. (JAMA Dermatol. 2013;149:166-76).
Although other studies in children support an association between obesity and psoriasis, the international study was the first to measure central adiposity, a more sensitive indicator of cardiovascular risk in children than BMI, Dr. Kelly Cordoro remarked in a separate lecture on the comorbidities of pediatric psoriasis at the meeting.
"Adiposity, hypertension, hyperlipidemia, and diabetes are increased in prevalence among pediatric psoriasis patients, but the obesity association is the strongest," she said. "It’s global, and the effect is most pronounced in the United States, where in particular, central obesity is highest and has the accompanying higher cardiovascular risk."
Previous research has shown that obesity is strongly correlated with psoriasis in adults. A recent meta-analysis showed that psoriatic adults were more likely to be obese than those without psoriasis (pooled odds ratio, 1.66), and that the odds were even higher in patients with severe versus mild psoriasis (OR, 2.23, vs. OR, 1.46) (Nutr. Diabetes 2012 ;2:e54).
Patrice Wendling/IMNG Medical Media
Dr. Kelly Cordoro
Both clinicians observed that psoriasis and obesity are chronic inflammatory states, marked by overexpression of circulating proinflammatory cytokines derived from Th1 and Th17 lymphocyte subsets, as well as tumor necrosis factor–alpha and adipokines. In addition, a fat cell is a microenvironment of inflammation, with adipose tissue releasing proinflammatory cytokines such as interleukin-6 and TNF-alpha.
The two diseases drive one another, but the exact relationship remains unclear, said Dr. Becker, a pediatrician and dermatology fellow at Northwestern at the time of the study. In addition, the impact on quality of life and social interactions of being both obese or overweight and having psoriasis may predispose patients to mental and physical health problems.
"Children with excess adiposity or with the highly visible lesions of psoriasis are more often teased or bullied, which may contribute to the tendency to become socially isolated, decrease physical activity, and increase eating," she said. "It really is a vicious circle."
Although the data are clear that psoriasis and obesity are associated, the current chart review suggesting that obesity precedes psoriasis is too small to definitively answer the question, Dr. Cordoro, a pediatric dermatologist at the University of California, San Francisco, said in an interview.
Dr. Becker said obesity clearly came before psoriasis in their study cohort, but agreed that further study is needed to confirm the results. She also stressed the need for biomarker analyses to identify overweight/obese children who are at risk for psoriasis, and studies to address whether weight loss can reverse the severity of pediatric psoriasis.
For example, data from a study of overweight psoriatic adults showed that eating a low-calorie diet improved psoriasis severity and quality of life after 4 months (JAMA Dermatol. 2013;149:795-801).
However, in the absence of adequate data, clinicians should consider metabolic testing to determine whether their overweight pediatric patients are on the path to the metabolic syndrome, Dr. Becker and Dr. Cordoro suggested. Metabolic testing was not performed on any of the 29 children in the chart review, although 48% had a family history of hyperlipidemia and 45% had a family history of obesity.
The average age of the children was 12.6 years; the average age of onset of obesity was 4 years (range, 2-12 years), and the average age of onset of psoriasis was 9 years (range, 2-14 years).
Two obese patients were able to reduce their BMIs from obese to overweight status 1 year after being diagnosed with psoriasis; however, both have remained in the 85th-95th BMI percentile for more than 2 years, Dr. Becker said. Both of the children who had a normal BMI prior to their psoriasis had a BMI in the overweight or obese range within 1 year after diagnosis, Dr. Becker noted.