Improvement in insulin resistance is greater when infliximab is added to methotrexate during intensive treatment of early rheumatoid arthritis - results from the IDEA study

Objectives: To determine the change in established biomarkers of cardiovascular (CV) risk, namely total cholesterol/high-density lipoprotein cholesterol ratio (TC/HDL-C), N-terminal pro-brain natriuretic peptide (NT-proBNP) and insulin resistance (IR) in patients with early rheumatoid arthritis (RA) treated with two different treat-to-target (T2T) strategies. Methods: Fasting glucose, lipids, insulin and NT-proBNP were measured at baseline, week 26 and 78 in 79 DMARD-naïve RA patients, free of CV disease (CVD), as part of a double-blind randomised controlled trial of methotrexate (MTX) with either infliximab (IFX) or methylprednisolone (MP) as induction therapy. Homeostasis model assessment-estimated insulin resistance (HOMA-IR) (glucose*insulin/405) was used to measure IR. Multiple imputation was employed, and linear regression analyses were adjusted for baseline values. Results: Changes in DAS44-CRP did not differ between the treatment arms at week 26 and 78. Mean TC/HDL-C, HOMA-IR and NT-proBNP improved in both groups at week 26 and 78, although change in NT-proBNP was not statistically significant at week 78. Changes in TC/HDL-C and NT-proBNP were similar between treatment arms, but HOMA-IR values in the IFX+MTX arm were 42% lower than those treated with MTX+MP at week 78 (p=0.003); difference remaining significant after adjustment for baseline body mass index, anti-citrullinated protein antibody positivity, smoking status and intra-muscular glucocorticoid use (p=0.007). Conclusions: When implementing a T2T approach, treatment of early RA was associated with improvement in TC/HDL-C, HOMA-IR and NT-proBNP, and a greater long-term improvement in HOMA-IR was seen in those treated with IFX.