CRP and ankylosing spondylitis: R-axSpA: radiographic-axial spondyloarthritis; RA: rheumatoid Arthritis; BASMI: Bath Ankylosing Spondylitis (AS) Metrology Index; BASDAI: Bath AS Disease Activity Index; BASFI: Bath AS Functional Index; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; NSAIDs: Non-steroidal anti-inflammatory drugs; NRS = numerical rating scale; HLA B27: Human Leukocyte Antigen-B 27; DAS28: Disease activity score 28; PGA: Patient global assessment.