Previous studies suggest that an increase in doses of weekly etanercept from 50 mg to 100 mg improves the efficacy of the treatment in patients with cutaneous psoriasis, rheumatoid arthritis, and psoriatic arthritis. In this same line of study, during the 2007 2008 period, we conducted a multicenter, double-blind, 12-week Study (LoadET, 0881A3-102090) comparing the efficacy of etanercept at a standard dose (50 mg/week) versus a double dose (100 mg/week) in subjects with AS refractory to conventional therapy. The interim results of said study do not appear to support the value of doubling the dose of etanercept in the treatment of subjects with AS. Once this study was finalised, the subjects continued to be monitored by their regular physician, who decided on the dose and treatment to follow according to the conditions of standard clinical practice. The objective of this observational study is to evaluate the course of the disease in the long-term (three years) under the conditions of standard clinical practice, in subjects who had participated in the LoadET study. Therefore, we would like to follow-up on those patients by reviewing their clinical histories for the three-year period between the finalisation of their participation in the LoadET Study (0881A3-102090) and now. This will allow us to assess the efficacy and survival of the drug, as well as the possible appearance of side effects in the three years following the finalisation of the study by comparing the results according to if the subjects had received 50 mg/week or 100 mg/week during the LoadET study (0881A3 102090). | 
