CRP and enthesitis: In univariate linear regression analysis, enthesitis (β = − 5.197, 95% CI -9.676, − 0.718) showed negative association, whereas psoriasis (β = 12.976, 95% CI 0.423, 25.529), CRP elevation (β = 6.220, 95% CI 2.332, 10.108), and average grade of sacroiliitis (average of right and left sacroiliitis; β = 4.823, 95% CI 3.076, 6.570) showed positive association with inflammatory SPARCC score of SIJ.