CRP and arthritic joint disease: After including potential confounders (sex, age, symptom duration, smoking habits, ESR, CRP levels, RF status, and ACPA levels) in the Cox regression model, the association between ultrasound-detected erosions and arthritis development remained statistically significant (HR 3.9, 95% CI 1.6–9.4, p = 0.003) (Figure 2).