A routine blood test may predict how well biologic drugs work for patients with axial spondyloarthritis, according to new Danish research.
The nationwide study examined C-reactive protein, or CRP, a standard inflammation marker. Researchers tracked over 3,300 patients who began treatment between 2015 and 2024.
Results showed a clear pattern. Higher baseline CRP levels predicted better treatment retention for patients starting tumor necrosis factor inhibitors, or TNFi. At one year, retention rates climbed from 63% to 72% as CRP increased.
For interleukin-17 inhibitors, however, CRP levels showed no significant impact on retention. Rates hovered around 51% to 55% regardless of baseline inflammation.
Remission rates improved with higher CRP for both drug classes. The findings suggest CRP can help set realistic treatment expectations. Up to half of axial spondyloarthritis patients have normal CRP at diagnosis.
This distinction matters for clinicians selecting initial therapy. TNFi candidates with elevated inflammation may see stronger outcomes. IL-17i effectiveness appears independent of baseline CRP.
The study analyzed data from Denmark's DANBIO registry. Researchers stratified patients into low, intermediate, and high CRP groups.
Key Findings:
- TNFi retention: 63% (low CRP) to 72% (high CRP)
- IL-17i retention: 51% (low CRP) to 55% (high CRP)
- Remission rates rose with CRP for both classes