Washington, May 11 : A new study has shed light on the effectiveness of medication given to children with juvenile rheumatoid arthritis (JRA), often thought to be incapable of treating the disease.

Children with JRA are being treated with the same drugs prescribed to adults with inflammatory diseases including corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), and disease-modifying antirheumatic drugs (DMARDs) such as methotrexate (MTX).

However, these medications fail to improve disease activity for many children with JRA.

Tumour necrosis factor (TNF) plays a key role in the inflammatory process. In the past decade, TNF-blockers have brought dramatic gains in treatment for rheumatoid arthritis patients. Etanercept, the only FDA-approved biologic for JRA patients until very recently, has also been proven highly effective and safe for children in short-term trials.

A collaborative study including over 70 pediatric rheumatology centres focussed on the etanercept drug in JRA patients for more than 8 years.

The study group began with a randomized controlled trial, focusing on 69 JRA patients between the ages of 4 and 17 years. Treatment with MTX and other DMARDs was discontinued a minimum of 2 weeks before enrollment, while maintaining a low-dose regimen of corticosteroids or NSAIDs was allowed.

The patients were given injections of etanercept based on the patient's body weight with a maximum weekly dosage of 50 milligrams.

As the trial extended beyond a year, participants were permitted to add low-dose MTX if recommended by their physician. At every 3 months during the first year of the extension phase, and then every 4 to 6 months during the following years.

They were assessed for improvement in overall disease status using the American College of Rheumatology Pediatric (ACR Pedi) criteria, as well as evaluated for changes in joint inflammation, mobility, pain, ability to perform routine daily tasks and C-reactive protein level. They also monitored for frequency of serious adverse events.

58 JRA patients, 84 percent of the participants in the randomized controlled trial, enrolled in the long-term extension trial and received weekly treatment for a total of 318 patient years of etanercept exposure. Most patients were female (67 percent) and white (74 percent), and all had taken MTX prior to the study.

The researchers found that 16 of the original 69 study participants reported 39 serious adverse events, for an overall exposure. This rate did not increase with long-term exposure to etanercept. Eight patients reported 9 medically important infections over the course of the long-term trial.

Patients who received 8 years worth of weekly etanercept treatment reported 70 percent improvement in joint symptoms.

"Continuous treatment with etanercept resulted in truly important, often profound, sustained improvement in all aspects of this disease including clinically important signs and symptoms of JRA, improvements in functional ability and decreased pain for up to 8 years," said study group spokesperson Dr. Daniel J. Lovell.