Increased mean C-reactive protein (CRP) levels are associated with accelerated progression to total joint replacement (TJR) in patients with rheumatoid arthritis (RA), UK researchers have revealed.
“Further, the change in serum CRP between low and high levels also appears correlated with progression to major surgical endpoints, suggesting that the risk is modifiable,” write Craig Currie (The Pharma Research Centre, Cardiff) and co-authors in the journal BMC Musculoskeletal Disorders.
Currie and team used routine laboratory data recorded in general practice to examine the effect of both average CRP and CRP change on progression to TJR in patients diagnosed with RA.
Patients with confirmed RA were selected from The Health Improvement Network (THIN) dataset and their CRP results were classified as either low (10mg/l or less) or high level (more than 10mg/l).
The researchers identified 2421 cases with at least one CRP measurement. Of these, 125 (5.2%) had at least one major joint replacement.
Regression models revealed that each unit increase in log mean CRP was associated with a 36% increase in the hazard ratio (HR) for TJR after controlling for confounding factors.
Repeated CRP observations around 1 year apart were recorded in 1287 patients, of whom 54 (4.2%) experienced at least one major joint replacement. The HR for TJR in cases with persistently high CRP was double that for stable low-CRP cases.
In patients whose CRP increased from low to high, the HR for joint replacement was 1.86 compared to those who remained in a low state. In contrast, the HR was more than halved in patients whose CRP was reduced from a high to low state, compared with to those who remained high.
Currie et al conclude: “The current observation that change in CRP modifies the risk of joint progression will be of interest to those assessing disease prognosis in rheumatoid disease.”
They add: “As this study could only demonstrate association and not causation, further studies will consider which therapeutic interventions control inflammation most effectively, and whether direct benefit in limiting progression to joint replacement can be characterized.”