This study examined whether response to tocilizumab (Actemra) is influenced by body mass index (a measure of the amount of muscle, fat and bone) in rheumatoid arthritis patients. 

Rheumatoid arthritis is an inflammatory disease affecting the joints, the connections between bones. It is an autoimmune disorder, which occurs when the immune system, the body’s defense against infection, starts attacking healthy tissue. The goal of drug therapy in rheumatoid arthritis is remission: a time when the disease is not active and damage to the joints is limited.

Some studies have shown that rheumatoid arthritis patients with a high body mass index do not respond as well to the rheumatoid arthritis drug infliximab (Remicade). Furthermore, animal studies suggest that high body mass index may also reduce patient response to tocilizumab (Actemra). This study aimed to investigate whether this was true in humans. 

This study involved 222 patients with rheumatoid arthritis who received tocilizumab treatment for 6 months. Patients were split into 3 groups based on their body mass index: 1) normal weight, 2) overweight, 3) obese.

The authors found that 41% of patients reached remission after 6 months of tocilizumab treatment, and the rest of the patients had a moderate to good response. The 6-month remission rates were 41% (obese), 28% (overweight), and 46% (normal weight). These remission rates were not significantly different between groups. Of note, tocilizumab induced significant weight gain over 6 months (almost 2 pounds on average). 

The authors concluded that body mass index does not affect response to tocilizumab.

Different nurses and doctors collected the body mass index and remission data. Therefore, there could be some variation in the data which may skew the results.