In children with arthritis, the time from diagnosis to the start of treatment with methotrexate appears to be an important predictor of their response to the drug at 6 months, Dutch investigators report.

“Our results suggest that earlier initiation of methotrexate treatment will lead to an increased response,” Dr. R. ten Cate, at Leiden University Medical Centre, and colleagues report in the journal Arthritis and Rheumatism.

So-called juvenile idiopathic arthritis, or JIA, strikes before the age of 16, causing pain, inflammation and cell damage in the lining of the joints. The disease may have a variety of symptoms and degree of severity. The cause of disease is not known but it is thought to be related to genetic and environmental factors.

In a look-back at 128 children with JIA, Dr. ten Cate’s group found that the overall response rate after 6 months of methotrexate treatment was 57 percent.

They also found that responders started methotrexate earlier and had worse symptoms than nonresponders. Even after analyzing the effect of prior treatments, such as steroids or sulfasalazine, earlier time to initiation of methotrexate was still significantly associated with response.

The researchers theorize that methotrexate can suppress early stages of inflammation in JIA and that the mechanism of action is less sufficient to control well-established chronic inflammation.

They call for further research “to determine if an increased early response leads to less joint damage in the long term.”

SOURCE: Arthritis and Rheumatism, January 15, 2009.