by Michelle Rizzo

Last Updated: 2007-11-13 16:11:23 -0400 (Reuters Health)

NEW YORK (Reuters Health) – Among patients with rheumatoid arthritis (RA), the level of disease activity at baseline and during the first 3 months of treatment is significantly associated with the level of disease activity at 1 year, according to findings published in the October issue of Arthritis & Rheumatism.

Dr. Josef S. Smolen, of the Medical University of Vienna, Austria, and colleagues analyzed pooled data from clinical trials involving 1342 patients with early RA treated with methotrexate (MTX), tumor necrosis factor (TNF) inhibitor monotherapy (adalimumab and etanercept), and combination TNF plus MTX.

The researchers used the Simplified Disease Activity Index (SDAI) as the primary assessment of disease activity, and found SDAI values at 1 year correlated significantly (p < 0.0001) with baseline values. Correlations increased at 3 months.

Average SDAI values were lower at all time points, including baseline, for those who achieved remission at 1 year compared to those whose disease activity was high at 1 year.

Correlations of baseline disease activity with values at 1 year were lower with TNF inhibitor plus MTX combination therapy, "indicating its effectiveness over a broader range of baseline disease activity."

The data were fully validated in late RA, using pooled data from clinical trials of MTX and of TNF inhibitor plus MTX involving 712 patients.

In an interview with Reuters Health, Dr. Smolen noted that his team had gained two major insights.

"First, there is a better chance of achieving low disease activity or remission if disease activity is on the lower side of the high disease activity range when starting therapy, especially with MTX," he pointed out.

"Second, and more importantly, it appears to just take 3 to 6 months of treatment to gain information on the longer-term efficacy," he said. "If by 3 to 6 months patients have not reached the low disease activity range, their chances of achieving remission are low," he said. "Since we see halt of joint damage on MTX only in remission, this is an important piece of information."

"By assessing their RA patients on a regular basis, such as every 3 months … physicians will be able to make therapeutic decisions within 3 to 6 months from start of a new treatment," Dr. Smolen concluded. "We would hope that this would allow more patients to reach the desired state of remission."

Arthritis Rheum 2007;56:3226-3235.