CRP and Sacroiliac arthritis: Multivariate regression analysis showed that psoriasis (β = 12.339, 95% CI 0.601, 24.078), CRP elevation (β = 3.893, 95% CI 0.113, 7.672), and average grade of sacroiliitis (β = 3.855, 95% CI 1.960, 5.750) were positively associated with inflammatory SPARCC score of SIJ.