Etanercept May Improve Growth for Kids With JIA

Kearsley-Fleet L, Hyrich KL, Davies R, et al., Growth in children and adolescents with juvenile idiopathic arthritis over 2 years of treatment with etanercept: results from the British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study. Rheumatology (Oxford). 2015 Jan 30. pii: keu489. [Epub ahead of print]

Children with juvenile idiopathic arthritis (JIA) often show delayed growth and short stature, but a new study shows etanercept (Enbrel) may help children with severe disease grow more quickly over the first 2 years of treatment.  

A study of almost 200 children with JIA, most of them girls around age 11, [[{"type":"media","view_mode":"media_crop","fid":"31883","attributes":{"alt":"juvenile arthritis","class":"media-image media-image-right","id":"media_crop_7038947816970","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"3362","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"width: 147px; height: 153px; float: right; margin: 3px;","title":" ","typeof":"foaf:Image"}}]]suggests that the tumor necrosis factor-alpha (TNF-α) blocker may have accelerated vertical growth velocity (the rate at which height increases) while inhibiting inflammation.

However, the change was not statistically significant and the etanercept (ETN)-treated children were still shorter than normal according to World Health Organization growth standards (height z-scores) for age and gender.

Corticosteroids may have inhibited growth for some children in the study, the researchers say.

The British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study involved 191 children recruited at 42 centers around the UK between 2004 and 2011 (some of the first children treated with ETN after it was approved for JIA in Europe). At the start of the study, 15% (n=29) were classified as short in stature. After six months, almost half (48%) showed minimal disease activity (MDA) by the Juvenile Arthritis Disease Activity Score (JADAS-71).

Over a two-year period, mean height velocity was 5.8 cm (around 2.30 inches) per year. Many of the kids grew faster than age- and gender-matched British peers. After two years, 9% (n=18) of the children were still shorter than normal. 

Those with the best outcomes were shortest and had been taking steroids at the outset. Interestingly, there was no significant relationship between growth rates and improvements in disease activity, which the authors say is worth looking into.