CRP and ankylosing spondylitis: IQR, interquartile range; VAS, visual analog scale; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; EMS, early morning stiffness; BAS-G, Bath Ankylosing Spondylitis Patient Global Score; ASDAS, Ankylosing Spondylitis Disease Activity Score; NSAID, non-steroidal anti-inflammatory drug; csDMARD, conventional synthetic disease-modifying anti-rheumatic drugs; ESR, erythrocyte sedimentation rate; CRP, C-reactive protein.