Epidemiology and burden of illness of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic, generally progressive autoimmune disease that causes functional disability, significant pain and joint destruction, and leads to premature mortality. It is estimated to affect between 0.5 and 1.0% of the adult population worldwide, increases in prevalence with age and affects more women than men. The magnitude of the severe long-term economic consequences of RA has been underestimated in the past. Most patients with the disease require continuous treatment to retard or stop progression and to control disease flares. Many also require surgery, such as total hip or knee replacement. In addition to these direct costs, work disability leads to reduced productivity and early retirement, and as a result, substantial indirect costs. The individual and his or her family must cope with the feeling of loss of contribution to society combined with redefined social roles, and the effects of pain, fatigue, low self-esteem, mental distress and depression. A number of countries in North America and Europe have reported a decline in the incidence of RA in recent years, although geographical differences remain that may be associated with genetic, environmental or cultural factors. Nevertheless, patients with RA have not shared the improvements in survival rates seen with other diseases over the last 40 years, and have a mean reduction in life expectancy of between 5 and 10 years. Disease severity, activity and disability are strongly linked to premature mortality in patients with RA. The high direct and indirect costs associated with RA, together with the substantial morbidity and mortality affecting millions of people worldwide, underline the potential benefits of improved treatments for this chronic disease to patients, their families and society.