Study Investigating Enbrel Treatment for Ankylosing Spondylitis

To identify the following problems and questions with respect to the safety and effectiveness of Enbrel during the post-marketing period as required by Korea Food and Drug Administration (KFDA)'s regulations. 1. Unknown adverse reactions, especially serious adverse reactions 2. Change of the incidences of adverse reactions under the routine drug uses 3. Factors that may affect the safety of the drug 4. Factors that may affect the effectiveness of the drug