Wyeth/Amgen's etanercept (Enbrel) and Abbott’s adalimumab (Humira) are both effective, well-tolerated treatments for juvenile rheumatoid arthritis, according to research presented this week at the American College of Rheumatology’s (ACR) Annual Scientific Meeting in Boston, USA.

In the first study, 69 children enrolled in a controlled clinical trial for juvenile rheumatoid arthritis were asked to participate in an open-label extension: 84% agreed. 61% and 38% of the 42 patients entered the 4th and 8th year of continuous etanercept treatment respectively.

Patient and guardian refusal emerged as the most common reason why children withdrew from the randomised controlled study or the extension (14.5%). Other children withdrew because of a suboptimal response (13.0%), physician decision (7.2%) or adverse events (7.2%).

23% of patients reported at least one adverse event. However, the overall rate of adverse events did not increase with long-term etanercept treatment. There were no cases of lupus, demyelinating disorders, tuberculosis or other opportunistic infections, malignancies or lymphomas, or deaths. The rate of medically important infections was lower in children than in previous studies that enrolled adults (0.03 and 0.10 patient years respectively).

The authors measured efficacy using the ACR paediatric criteria. After seven years, 90% of children achieved ACR 30 and 50 (a 30% and 50% improvement in the criteria respectively). In addition, 86%, 67%, and 29% of the children attained ACR 70, 90 and 100 respectively.

The second study involved 171 patients with polyarticular juvenile rheumatoid arthritis. Patients received adalimumab (24 mg/m2 body surface area; maximum 40 mg every other week) for 16 weeks. At the end of this open-label phase, 84% and 77% achieved an ACR-paediatric rating of 30 and 50 respectively, while 58% and 27% achieved ACR 70 and 90 respectively.

Those who showed at least ACR 30 entered a double-blind phase where they received either adalimumab or placebo every other week for 32 weeks or until disease flare. At the end of the double-blind phase, 60%, 59%, and 56% of those receiving adalimumab achieved ACR 30, 50, and 70 respectively. This compared with 35%, 35%, and 28% in the placebo arm. Furthermore, more patients in the placebo arm flared.

Most patients (128) then entered an open-label extension phase. After a year, 94% and 93% achieved ACR 30 and 50 respectively, while 81% and 60% showed ACR 70 and 90 respectively. Methotrexate, which some children took concurrently, did not seem to influence the outcome and adalimumab was well tolerated.

About one child in every 1,000 under the age of 16 years develops juvenile arthritis. Juvenile rheumatoid arthritis is the most common rheumatic disease among children and is a painful, progressive disease that can leave sufferers permanently disabled.