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08-11-2011 | Immunology | Article

Factors predicting response to etanercept in JIA patients uncovered


Free abstract

MedWire News: Having a low baseline disability score, taking fewer disease-modifying antirheumatic drugs (DMARDs), and having a younger age at disease onset predict excellent response to etanercept therapy in children with juvenile idiopathic arthritis (JIA), show study results.

By contrast, having systemic JIA and being of female gender was associated with a poor response to the drug.

Etanercept has been approved for treatment of JIA by the US Food and Drug Administration for a decade and has been shown to improve outcomes in at least 70% of children with JIA by 30% or more.

"However, inactive disease is still not achieved in a substantial proportion of cases, and current approaches need to be optimized even more," write Marieke Otten (Erasmus Medical Center Sophia Children's Hospital, Rotterdam, the Netherlands) and colleagues in JAMA.

They therefore investigated whether different baseline factors might predict the success of etanercept therapy in young people with JIA. They followed-up 262 patients with the condition who were enrolled in the Arthritis and Biologicals in Children Register, which began in 1999 and includes all Dutch JIA patients prescribed biological therapy.

The team assessed response to etanercept at 15 months after treatment initiation. At this point, 32% of the patients had an excellent response (inactive disease), 36% had an intermediate response (more than 50% improvement from baseline), and 32% had a poor response (less than 50% improvement from baseline) to the therapy.

Children with an excellent response had lower baseline disability scores than others; indeed, analysis showed the adjusted odds for an excellent response was 60% lower for each point increase (worsening) of disability score relative to better scores.

In addition, children who had an excellent response took fewer DMARDs, with the odds for such response being 36% lower for each additional DMARD used, and were younger at disease onset, with the odds being 8% lower for each additional year of age.

By contrast, having systemic JIA and being female increased the risk for having a poor response to etanercept 2.92- and 2.16- fold, respectively.

Adverse events were relatively common, as 119 patients experienced one or more infectious, noninfectious, or serious adverse events over 15 months of treatment, with 61 patients discontinuing etanercept due to side effects. Most of the children who stopped taking etanercept had a poor response to the drug (n=57).

"The ability to identify patients who are more likely to respond to etanercept treatment would be an important step toward tailored patient-specific treatment and subsequently could improve current treatment approaches," says the team.

They concede that the lack of a control group was a weakness in this study, but say that their results are useful for predicting which children with JIA will gain most from etanercept.

By Helen Albert

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