CRP and ankylosing spondylitis: ETN, etanercept; IV, intravenously; ASAS, ASsessment in AS; ankylosing spondylitis; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; BASDAI, Bath AS Disease Activity Index; BASMI, Bath AS Metrology Index; BASFI, Bath AS Functional Index; MRI, magnetic resonance imaging.