CRP and ankylosing spondylitis: VAS, visual analogue scale; ESR, erythrocyte sediment rate; CRP, C-reactive protein; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; ASDAS, Ankylosing Spondylitis Disease Activity Score; DMARD: Disease-modifying anti-rheumatic drug; MTX, sulfasalazine; SSZ, Sulfasalazine.