Rheumatoid arthritis is a disease in which immune cells, that normally work to protect our body, mistakenly attack healthy cells in our joints. They can cause pain and joint deformities. In Europe and the United States, the number of new cases of rheumatoid arthritis is increasing, affecting 1 in every 100 to 200 people each year. In Japan, 80% of all patients are women and the onset age is surprisingly young, peaking in the 40s. The cause of the disease is still unclear and it is difficult to diagnose rheumatoid arthritis in its early stages. What are the signs to look out for and when should you see a doctor? Find out some tips that can help lead to the early diagnosis of rheumatoid arthritis.