Abstract
Objective
To determine whether C-reactive protein (CRP) measured by a high sensitivity (hs) assay is a surrogate marker of disease activity and damage in systemic lupus erythematosus (SLE).
Methods
Five hundred eighty-eight patients with SLE participating in a multiethnic cohort (Hispanic, African American, and Caucasian) were studied. Disease activity was measured with the Systemic Lupus Activity Measure-Revised (SLAM-R) and damage with the Systemic Lupus International Collaborating Clinics (SLICC) Damage Index (SDI). hs-CRP was measured by immunometric assay. Disease activity and hs-CRP were measured at enrollment and damage accrual at last visit. The association of hs-CRP with the SLAM-R and SDI was examined by univariable (Pearson’s correlation) and multivariable (linear regression) analyses. The association of hs-CRP and each individual domain of the SLAM-R and SDI was examined by Spearman’s correlation.
Results
hs-CRP was associated with the SLAM-R in the univariable (r = 0.35, p < 0.001) and multivariable (t = 7.11, coefficient β = 0.27, p < 0.001) analyses. It also correlated with the constitutional, eye, pulmonary, gastrointestinal, neuromotor, and laboratory domains of the SLAM-R. hs-CRP was associated with the SDI (r = 0.12, p = 0.004) in the univariable analysis but not in the multivariable analysis. When the individual domains of the SDI were analyzed, hs-CRP correlated with the renal, pulmonary, cardiovascular, musculoskeletal, and diabetes domains.
Conclusion
hs-CRP was associated with disease activity but not with overall damage accrual; however, it correlated with specific domains of the damage index. hs-CRP may be useful to monitor the course of the disease and predict its intermediate outcome, but longitudinal studies with serial hs-CRPmeasurements are necessary to define its clinical value.
Key Indexing Terms:Footnotes
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A.M. Bertoli, MD, Adjunct Professor of Medicine, University of Puerto Rico Medical Sciences Campus; L.M. Vilá, MD, Professor of Medicine, Chief and Program Director of Rheumatology, University of Puerto Rico Medical Sciences Campus; J.D. Reveille, MD, Professor of Internal Medicine, George H. Bruce, Jr. Professor in Arthritis and Other Rheumatic Diseases, Director, Division of Rheumatology and Clinical Immunogenetics, University of Texas Health Science Center at Houston; G.S. Alarcón, MD, MPH, Professor of Medicine, Jane Knight Lowe Chair of Medicine in Rheumatology, University of Alabama at Birmingham.
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Supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases P01-AR49084, General Clinical Research Centers M01-RR02558 (UTH-HSC) and M01-RR00032 (UAB), the National Center for Research Resources (NCRR/NIH) RCMI Clinical Research Infrastructure Initiative (RCRII) award 1P20 RR11126 (UPRMSC), and by an unrestricted educational grant from Bristol-Myers Squibb Company (UPR-MSC).
- Accepted for publication July 28, 2008.
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