The main effect shows that both tenderness and pain are significantly greater in fibromyalgia than in rheumatoid arthritis/systemic lupus erythematosus. However, the interaction shows that (a) this difference is greater in fibromyalgia (FM) than in rheumatoid arthritis/systemic lupus erythematosus (RA/SLE) and (b) tenderness is more severe than pain in FM, whereas pain predominates over tenderness in RA/SLE. The healthy control values are provided for background comparison. HLTH, healthy controls.
Friend and Bennett Arthritis Research & Therapy 2011 13:R58 doi:10.1186/ar3311