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Assessing polymyalgia rheumatica activity when C-reactive protein is unavailable or uninterpretable
Valérie Devauchelle-Pensec1,2, Lea Saraux1,3, Jean Marie Berthelot4
1Rheumatology Department, CHU Brest,, Brest, France.
Rheumatology (Oxford, England)
|January 19, 2018
Summary
New polymyalgia rheumatica activity scores (PMR-AS) were developed without C-reactive protein (CRP) for patients on anti-IL-6 therapy. These CRP-independent scores accurately monitor PMR disease activity in clinical practice.
Area of Science:
- Rheumatology
- Clinical Trial Methodology
- Biomarker Validation
Background:
- The Polymyalgia Rheumatica Activity Score (PMR-AS) relies on C-reactive protein (CRP), which is often unavailable or invalid during anti-interleukin-6 (IL-6) therapy.
- This limitation hinders accurate monitoring of polymyalgia rheumatica (PMR) disease activity in patients receiving specific treatments.
Purpose of the Study:
- To develop and validate alternative PMR activity scores that do not require CRP measurements.
- To enable reliable assessment of PMR activity in patients undergoing anti-IL-6 therapy or with missing CRP data.
Main Methods:
- Utilized two patient cohorts (CRI and TENOR) with PMR.
- Correlated PMR-AS components to impute CRP values, creating a CRP-imputed PMR-AS (CRP-imp PMR-AS).
- Evaluated the agreement between the original PMR-AS, a CRP-independent clinical PMR-AS (clin-PMR-AS), and the CRP-imp PMR-AS in both cohorts.
Main Results:
- Excellent agreement (κ = 0.90) was observed between PMR-AS and clin-PMR-AS in the CRI cohort.
- The developed CRP-imp PMR-AS showed closer agreement with the original PMR-AS compared to clin-PMR-AS.
- Validation in the TENOR cohort confirmed the utility of CRP-imp PMR-AS and ESR-PMR-AS during tocilizumab treatment.
Conclusions:
- Alternative PMR activity scores that exclude CRP are feasible and reliable.
- These CRP-independent scores can be effectively used in routine clinical practice for monitoring PMR activity.
- The findings support the use of these modified scores for patients with unavailable CRP values or on IL-6 antagonist therapy.
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