IL6R and rheumatoid arthritis: This post hoc analysis of MONARCH phase III randomized controlled trial data evaluated the potential of baseline IL-6 levels to differentially predict HRQoL improvements with sarilumab, a fully human monoclonal antibody directed against both soluble and membrane-bound IL-6 receptor α (anti-IL-6Rα) versus adalimumab, a tumor necrosis factor α inhibitor, both approved for treatment of active RA.