Higher BMI Equals Lower Response to RA Therapy

August 8, 2013

Recent-onset rheumatoid arthritis (RA) patients who weigh too much may get too little benefit from disease modifying antirheumatic drugs (DMARDs) and tumor necrosis factor α (TNF-α) blockers, according to a randomized clinical trial.

Heimans L, Broek M, Cessie S, et al. Association of High Body Mass Index With Decreased Treatment Response to Combination Therapy in Recent-Onset Rheumatoid Arthritis Patients. Arthritis Care & Res. (2013) 65:1235–1242. DOI: 10.1002/acr.21978  [Epub July 26]

Recent-onset rheumatoid arthritis (RA) patients who weigh too much may get too little benefit from disease modifying antirheumatic drugs (DMARDs) and tumor necrosis factor α (TNF-α) blockers, according to a randomized clinical trial from the Netherlands.

A cohort of 508 DMARD-naive patients with early RA -- 216 with a body mass index (BMI) of <25 kg/m2 and 292 with a BMI ≥25 kg/m2 -- had initially been randomized to one of four treatment groups, including combination therapy with methotrexate (MTX) and the TNF-α blocker infliximab (IFX).

Response to the Disease Activity Score (DAS) of ≤2.4 steered therapy over the first year, with adjustments every three months if the DAS stayed higher than 2.4.

After a year, those with a high BMI were more likely to have an impaired response to conventional antirheumatic therapy than those with a low/normal BMI, and to require more adjustments in treatment. This was especially true for MTX in combination with other DMARDs.

Overweight or obese patients were also more than twice as likely not to reach a low DAS (≤2.4) with initial MTX-IFX combination therapy. No significant difference was seen among the initial MTX monotherapy groups.
 
In the first year, patients with BMI greater than 25 also had higher disease activity, more pain, greater numbers of tender joints, worse functional ability, and a higher visual analogue scale (VAS) assessment of global health and quality of life.

However, high BMI patients did not have more swollen joints or inflammation than those with a low/normal BMI in the first year. Radiologic damage progression in the first year and over 8 years of follow-up were similar in both groups. The reasons for this are unclear.