Obesity may weaken effect of antirheumatic drugs

Obese rheumatoid arthritis (RA) patients taking conventional synthetic (cs-) or biological disease-modifying antirheumatic drugs (DMARDs) see lower rates of disease remission, a recent study has shown.

Drawing from five trials, the researchers examined the effect of either tocilizumab and/or csDMARDs on 5,502 RA patients, categorized according to baseline body mass index (BMI). The percentages of participants who were overweight (32.8 percent), obese (30.4 percent, and of normal BMI (33.9 percent) were similar, while only 2.9 percent were underweight. The primary study outcome was time to first RA remission.

A higher BMI correlated significantly with less frequent disease remission, as defined by both the simplified (SDAI) and clinical (CDAI) disease activity indices (p=0.001 for both).

Specifically, Cox proportional hazards analysis revealed that obese RA patients were 20-percent less likely to see disease remission, as defined by SDAI (adjusted hazard ratio [HR], 0.80, 95 percent confidence interval [CI], 0.80–0.92). The same was true when remission was defined according to the CDAI, and with a slightly stronger magnitude of effect (adjusted HR, 0.77, 95 percent CI, 0.68–0.87).

Signals of lower remission were also observed in underweight participants, though statistical significance was not achieved (SDAI: adjusted HR, 0.83, 95 percent CI, 0.57–1.19; CDAI: adjusted HR, 0.85, 95 percent CI, 0.63–1.15).

The findings of the present study indicate that adipose tissue may play a role in the pathophysiology of RA, they explained, adding that clinicians should take BMI into consideration when stratifying patients for treatment. Future investigations are needed to examine the impact of weight loss on DMARD efficacy.