Association of C-reactive protein with osteoarthritis: Evidence from a retrospective analysis

Osteoarthritis (OA) is a common chronic inflammatory joint disease that severely affects the quality of life in middle-aged and older adults. C-reactive protein (CRP) is a classical inflammatory biomarker; however, its cross-sectional association with the presence of OA remains unclear. This study aimed to evaluate the association between CRP and other blood markers with prevalent OA in a hospital-based population. A total of 8652 participants were included in this retrospective cross-sectional study. Multivariable logistic regression models were used to assess the association between CRP and OA, and restricted cubic spline regression was applied to examine dose–response relationships. Subgroup analyses were conducted to explore potential heterogeneity of associations. CRP levels were linearly and positively associated with the presence of OA ( P < .001), and this association remained statistically significant after multivariable adjustment (odds ratio = 1.013, 95% confidence interval = 1.006–1.021). Restricted cubic spline analysis revealed a linear association between CRP and OA, whereas white blood cell count exhibited a nonlinear pattern. Although statistically significant, the effect size was small, indicating limited clinical relevance at the individual level. In this retrospective cross-sectional study, CRP levels were modestly associated with prevalent OA among hospital-attending adults in China. These findings support an association between systemic inflammation and OA but should be interpreted cautiously given the lack of temporal ordering and potential residual confounding.