EPIDEMIOLOGY

RA is a worldwide problem with a prevalence in Europe and North America of 0.5% to 1% of the adult population and an annual incidence of 25 to 50/100,000. RA is at least twice as common in women as in men and has a higher prevalence in specific patient populations such as the Pima and Chippewa Native Americans, with a respective prevalence of 5.3% and 6.8%. The disease affects individuals at any age, but most common age of onset is between 50 and 60 years. RA is uncommon among men younger than 45 years of age, but the incidence rises steeply with increasing age. Poor prognostic factors include high disease activity with many joints involved, increased inflammatory markers, high titers of rheumatoid factor (RF) and/or cyclic citrullinated peptides (CCP) antibodies, tobacco use, and erosions on radiographs. With the advent of new therapies, disease severity has decreased over time with less marked radiographic damage and fewer major orthopedic surgeries including joint replacements. However, despite these advances, work-related disability rates remain high for patients with RA. Numerous studies have demonstrated increased mortality rates for patients with RA compared with the general population, with a relative risk of 1.3. The increased mortality rate is more pronounced in males than in females with RA and is attributed to infectious complications and cardiovascular disease.