A study that evaluated children with severe juvenile idiopathic arthritis before and after starting anti-tumor necrosis factor treatment indicated that these biological agents appear to be effective in restoring normal growth in this population, reported Dr. Pirjo Tynjälä.
The results also suggest that the improvements in growth are related to the impact these treatments have on inflammation, wrote Dr. Tynjälä of the Hospital for Children and Adolescents, Helsinki University Central Hospital, and her associates (Ann. Rheum. Dis. 2006;65: 1044–9).
The study followed the growth of 71 children with polyarticular disease-course juvenile idiopathic arthritis for 2 years before and 2 years after starting etanercept (43 patients) or infliximab (28 patients). When treatment started, mean age was 9.6 years, mean disease duration was 5.7 years, and the children were refractory to conventional disease-modifying antirheumatic drugs. The dose of etanercept (Enbrel) was 0.4 mg/kg twice a week; the dose of infliximab (Remicade) was 80–200 mg every 6–8 weeks administered intravenously.
In the group overall, the mean growth velocity increased significantly during treatment, which was mostly because of the increase in the 53 children whose growth was delayed before starting treatment. Among the 18 children whose growth was normal or accelerated before treatment, growth velocity increased, but not significantly, during treatment. Over the 4 years, there were no significant differences in the total steroid dose among those with delayed growth and those with normal growth.
After 24 months of treatment, disease was inactive in 52% of the patients, and activity had decreased in the remainder, Dr. Tynjälä and her colleagues wrote.
The change in inflammatory activity “remained a significant predictor of the growth velocity, even after glucocorticoids were taken into account,” suggesting that the improved growth velocity may be because of the reduction in inflammation and not “a direct effect of biological agents on growth or on skeletal maturation.”