Femoral bone mineral density as a tool of personalized medicine for rheumatoid arthritis: Interleukin-6 inhibitors for patients with low density whereas tumor necrosis factor inhibitor for patients with preserved density?

Objectives: There is a lack of indicators to distinguish between interleukin-6 inhibitors responders and tumor necrosis factor inhibitors responders in the treatment of rheumatoid arthritis. Osteoporosis is a complication of rheumatoid arthritis and is closely related to inflammatory pathology. The purpose of this study was to evaluate whether bone mineral density can distinguish interleukin-6 inhibitors responders from tumor necrosis factor inhibitors responders in rheumatoid arthritis.

Methods: Either interleukin-6 inhibitors or tumor necrosis factor inhibitors was introduced as the first biologics to patients naïve to both corticosteroid and osteoporosis treatment. Correlations between baseline bone mineral density and Clinical Disease Activity Index after 3 months were analyzed.

Results: The subjects were 26 rheumatoid arthritis patients with a median age of 60 years old, disease duration of 1.4 years, Clinical Disease Activity Index of 13.7, and C-reactive protein of 1.69 mg/dL. The subjects were divided into two groups (high (H) and low (L)) according to their femoral bone mineral density with a cutoff of young adult mean of 80%. Six in group H and 11 in group L received interleukin-6 inhibitors, and nine in group H received tumor necrosis factor inhibitors. Clinical Disease Activity Index remission rate by interleukin-6 inhibitors was significantly greater in group L (8/11 (72.7%)) than in group H (1/6 (16.7%); p < 0.05). In the whole group H, significantly more patients obtained Clinical Disease Activity Index remission by tumor necrosis factor inhibitors (7/9, 77.8%) than by interleukin-6 inhibitors (1/6 (16.7%); p = 0.04).

Conclusions: In patients with rheumatoid arthritis, interleukin-6 inhibitors may be more beneficial for patients with low femoral bone mineral density, whereas tumor necrosis factor inhibitors may be advantageous for those with preserved bone mineral density.