Does hsCRP provide insights into an inflammatory phenotype of knee osteoarthritis?
Navya George1, Jean W Liew2, Na Wang3
1Department of Internal Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, United States.
Insights
High-sensitivity C-reactive protein (hsCRP) does not reliably identify knee inflammation in osteoarthritis (OA). This study found no association between hsCRP levels and synovitis, suggesting it may not be a useful biomarker for inflammatory OA phenotypes.
Area of Science:
- Orthopedics
- Rheumatology
- Biomarker Discovery
Background:
- Elevated high-sensitivity C-reactive protein (hsCRP) has been linked to reduced joint replacement risk in patients with cardiac disease and OA.
- Identifying an inflammatory phenotype in osteoarthritis (OA) is crucial for targeted therapies.
Purpose of the Study:
- To determine if hsCRP can serve as a biomarker for identifying an inflammatory OA phenotype characterized by intra-articular synovitis.
- To assess the relationship between hsCRP levels and the presence and severity of knee inflammation.
Main Methods:
- Analysis of data from the MOST Study, including baseline knee MRIs and hsCRP assays.
- Inflammation scoring using the Whole Organ MRI Score (WORMS), focusing on synovitis and effusion.
- Logistic and linear regression analyses to examine the association between hsCRP and inflammation, adjusted for covariates.
Main Results:
- No significant association was found between hsCRP levels (continuous or dichotomized) and the presence or average score of knee inflammation.
- Cubic spline regression and ROC curve analysis indicated poor predictive ability of hsCRP for identifying MRI-defined synovitis.
- The study included 792 participants with a mean age of 62, where 41% had hsCRP ≥2mg/dL and 28% of knees showed inflammation.
Conclusions:
- hsCRP levels do not reliably identify knees with inflammation in the context of OA.
- Further research is needed to explore hsCRP's potential role in predicting treatment response for inflammation not directly related to synovitis.
Objective:
Posthoc analysis of a canakinumab trial showed a risk reduction of joint replacement in participants with cardiac disease and elevated hsCRP (≥2mg/dL). We determined if hsCRP could serve as a marker to identify an inflammatory OA phenotype characterized by intra-articular synovitis.
Method:
We used data from the NIH-funded MOST Study, where participants had baseline knee MRIs and hsCRP assays. Inflammation was scored using the Whole Organ MRI Score (WORMS), with presence defined as Hoffa's synovitis or effusion-synovitis score ≥2 in ≥1 of 3 locations. We examined the relationship between hsCRP and inflammation presence using logistic regression, and the average inflammation score with linear regression. Analyses were repeated with hsCRP categorized as ≥2mg/dL vs. <2mg/dL. Cubic spline regression and ROC curve were completed. Analyses were adjusted for age, sex, and body mass index.
Results:
Out of 792 participants (mean age 62, 52% female), mean hsCRP was 2.98 mg/dL, with 41% having hsCRP ≥2mg/dL. Inflammation was present in 28% of knees. No association was found between hsCRP levels and inflammation presence (odds ratio 0.99, 95% confidence interval 0.96-1.01) or average score, including with dichotomized hsCRP. Cubic spline regression did not reveal non-linear associations. The ROC curve suggested poor predictive ability of hsCRP to identify knees with inflammation on MRI.
Conclusion:
Despite interest in identifying an inflammatory phenotype in OA, hsCRP levels do not reliably identify knees with inflammation. Further investigation is needed to determine if hsCRP can predict knee response to therapies targeting inflammation not directly related to synovitis.
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