RA is the most common form of autoimmune arthritis, affecting more than 1.3 million Americans. Of these, about 75 percent are women. In fact, 1–3 percent of women may get rheumatoid arthritis in their lifetime. The disease most often begins between the fourth and sixth decades of life. However, RA can start at any age. - See more at: http://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Rheumatoid-Arthritis#sthash.Wi9PmM4G.dpuf