Obesity is associated with an increased rate of paediatric MS and more relapses on first-line treatment, research shows.

And findings support other evidence that obesity doubles the MS risk in adult populations.

A single-centre, retrospective German study of 453 paediatric patients with relapsing-remitting MS found 27.8% of the children were overweight or obese within six months of their first clinical presentation.

The children had an average age of 13.7 years at diagnosis and were mostly female (67.5%).

About half the children with high BMI (13%) were determined to be overweight and about half (14.8%) were obese.

The study found that high BMI was associated with an increased odds of paediatric MS in both girls and boys.

“This association was dose dependent and had an OR of 1.37 (95% CI, 1.0-1.8; P = 0.03) in overweight participants and rose to 2.2 (95% CI, 1.7-2.9; P < 0.001) in those with obesity, an outcome seen equally in boys and girls,” the study authors said.

Higher rates of overweight and obesity were seen in both younger (7-10 years) and older aged children (11-17 years).

Younger boys had the highest rate of overweight and obesity (40%).

The study also found more relapses on interferon or glatiramer therapy for obese children compared to non-overweight children.

“This finding was statistically significant for children younger than 11 years and adolescents aged 11 to 17 years.”

“Extremely obese patients (BMI >99.5th percentile; n = 20) had the worst response to interferon beta and glatiramer therapy (ARR, 1.37; 95%CI, 1.0-1.9; P < 0.001).”

The researchers said that the switch rate to a second-line disease-modifying therapy (DMT) was approximately 50% higher in obese children.

“All children who were obese at diagnosis were still displaying high BMIs at therapy escalation. The likelihood of receiving a second-line DMT was approximately 1.5 times higher among obese (21 [56.8%] of 37) and extremely obese (11 [61.1%] of 18) patients compared with non-overweight patients (48 [38.7%] of 124).”

No BMI association was shown for disease activity on baseline brain or spine MRI, interval between first and second MS attacks, or EDSS score progression.

“Without evidence of higher disease activity, the suboptimal treatment response observed in this study may be associated with altered drug pharmacokinetics in obese patients,” the study authors wrote in JAMA Neurology.

“Studying the association of obesity with the pharmacokinetics of first-line DMTs may improve the understanding of treatment response in obese patients and possibly even enable the development of BMI-adjusted dosing recommendations.”

They concluded patients should first be encouraged to achieve a healthy body weight in order to improve their response to therapy.