[Epidemiology of collagen diseases].

Collagen diseases have been generally thought to be rare, but the number of patients with rheumatoid arthritis(RA) becomes over 700,000 in recent days. In addition, the survival rate has markedly increased, but many lupus patients are still suffering from so called intractable organ involvements such as severe lupus nephritis and CNS lupus, etc. The main purposes of the treatment for RA are to prevent bone/cartilage destruction, to improve the quality of life(QOL) of patients, and to improve prognosis. For these purposes, new type of drugs such as biologic agents are introduced, and showing remarkable effects comparing with conventional DMARDs. But the side effects and cost of these agents are becoming problems. To overcome these problems, the epidemiology that can clearly show the benefits of these agents on daily life of patients is becoming much more important issue.