CRP Level Can Predict Treatment Outcome in Ankylosing Spondylitis
C-reactive protein (CRP) levels can be strong predictors of how a patient with ankylosing spondylitis (AS) will respond to tumor necrosis factor-α blocker treatment, according to results of a post hoc analysis.
“In patients with AS, both baseline and post-baseline CRP levels can be predictive of response to treatment at week 12, more consistently than patient-reported outcomes,” the researchers wrote.
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From 4 randomized trials, the researchers gathered data on 867 participants with AS treated with etanercept.
Among all participants, baseline CRP levels were normal in 43% (n=371), high in 34% (n=299), and very high in 23% (n=197).
CRP levels were considered normal at upper limit of normal (ULN) or below, elevated if higher than the ULN, high if higher than the ULN and 3 times the ULN or less, and very high if more than three times the ULN.
The researchers evaluated CRP levels at 2, 4, and 8 weeks. In addition, baseline CRP levels and levels of patient-reported outcomes were assessed in relation to responses at 12 weeks.
A very high baseline CRP was found to be a significant predictor for all 4 week-12 outcomes compared with normal CRP levels. Yet, a normal CRP at 2, 4, and 8 weeks was a stronger predictor of response at 12 weeks than elevated CRP.
Both were more consistent predictors of response than a patient-reported outcome.
Associations between higher baseline CRP and developing AS before 40 years of age, as well as between having normal CRP and lower disease burden, were also significant.
Baraliakos X, Szumski A, Koenig AS, Jones H. The role of C-reactive protein as a predictor of treatment response in patients with ankylosing spondylitis. [published online November 2, 2018]. Semin Arthritis Rheum. https://doi.org/10.1016/j.semarthrit.2018.10.019.