Relation between red blood cell distribution width and inflammatory biomarkers in rheumatoid arthritis.
We measured RDW, CRP, and ESR in 561 patients with RA and 131 patients with osteoarthritis (Table 1). The RDW was determined using an XE-2100 (Sysmex, Kobe, Japan), and the ESR was measured with Westergren method (StaRRsed III, Mechatronics Instruments, Hoorn, the Netherlands). C-reactive protein concentration was quantified using a nephelometer (BNII, Dade Behring/Siemens Healthcare Diagnostics, Marburg, Germany). Because CRP and ESR were not normally distributed, they were logarithmically transformed, and we used linear regression analysis. There were correlations between RDW and both CRP and ESR in patients with RA. However, in patients with osteoarthritis, RDW did not show any correlation with ESR but showed correlation with CRP (Table 2). Because most of the CRPs measured in patients with osteoarthritis patients were at values below detection limits (0.3 mg/dL), the results were not significant. Anemia affects the value of ESR; therefore, we divided RA cases into anemic and nonanemic groups. Correlations between RDW, CRP, and ESR were determined using correlation coefficients for 341 cases in the anemic group (men, hemoglobin ,13 g/dL; women, hemoglobin ,12 g/dL) and 220 cases in the nonanemic group. Regardless of the presence of anemia, RDW showed correlation with CRP but no correlation with ESR (Table 3).
In the RA cases grouped according to RDW quartiles, there were graded associations of RDW with CRP and ESR, but when divided into anemic and nonanemic cases, there was graded association of RDW with CRP but not with ESR in both groups. Unlike the results measured by Lippi and colleagues1 in unselected outpatients, RDW is thought to be affected by anemia in patients with RA.
WOONG SOO LEE,MD
Department of Laboratory Medicine
Hanyang University Medical Center
Seoul, Republic of Korea
(1.) Lippi G, Targher G, Montagnana M, Salvagno GL, Zoppini G, Guidi GC. Relation between red blood cell distribution width and inflammatory biomarkers in a large cohort of unselected outpatients. Arch Pathol Lab Med. 2009;133(4):628-632.
(2.) Tonelli M, Sacks F, Arnold M, Moye L, Davis B, Pfeffer M. Relation between red blood cell distribution width and cardiovascular event rate in people with coronary disease. Circulation. 2008; 117(2):163-168.
(3.) Perlstein TS, Weuve J, Pfeffer MA, Beckman JA. Red blood cell distribution width and mortality risk in a community-based prospective cohort. Arch Intern Med2009;169(9):588-594.
(4.) Matsui T, Kuga Y, Kaneko A, et al. Disease Activity Score 28(DAS28) using C-reactive protein underestimates disease activity and overestimates EULAR response criteria compared with DAS28 using erythrocyte sedimentation rate in a large observational cohort ofrheumatoid arthritis patients in Japan. Ann Rheum Dis. 2007;66(9):1221-1226.
(5.) Nurmohamed MT. Cardiovascular risk in rheumatoid arthritis. Autoimmun Rev. 2009;8(8): 663-667.
The authors have no relevant financial interest in the products or companies described in this article.
Table 1. Characteristics of Population Parameter RA (n = 561) Age, y (range) 50.9 (13-85) Women, No. (%) 484 (86.3) Hemoglobin, g/dL (range) 12.3 (7.8-17.1) RDW (RR, <14.5%), % (range) 13.8 (11.1-24.0) CRP (RR, <0.3 mg/dL), mg/dL (range) 2.2 (0.3-18.5) ESR (RR, <30 mm/h), mm/h (range) 38.8 (2-139) Parameter OA (n = 131) Age, y (range) 59.5 (39-80) Women, No. (%) 114 (87.0) Hemoglobin, g/dL (range) 13.5 (12.0-16.4) RDW (RR, <14.5%), % (range) 12.7 (11.4-14.8) CRP (RR, <0.3 mg/dL), mg/dL (range) 0.36 (0.3-2.3) ESR (RR, <30 mm/h), mm/h (range) 15.5 (2-68) Abbreviations: CRP, C-reactive protein;ESR, erythrocyte sedimentation rate; RA, rheumatoid arthritis; RDW, red blood cell distribution width; RR, reference range; OA, osteoarthritis. Table 2. Correlations Between Red Blood Cell Distribution Width (RDW), C-reactive Protein (CRP), and Erythrocyte Sedimentation Rate (ESR) in Rheumatoid Arthritis and Osteoarthritis RDW in Rheumatoid Arthritis (n = 561) Parameter Regression Equation r P log CRP y = 0.878x + 13.77 0.294 <.001 log ESR y = 0.891x + 12.84 0.191 <.001 RDW in Osteoarthritis (n = 131) Parameter Regression Equation r P log CRP y = 1.194x + 13.30 0.321 <.001 log ESR y = 0.009x + 12.71 0.006 .95 Table 3. Correlations Between Red Blood Cell Distribution Width (RDW), C-reactive Protein (CRP), and Erythrocyte Sedimentation Rate (ESR) in Rheumatoid Arthritis RDW Without Anemia (n = 341) Parameter Regression Equation r P log CRP y = 0.584x + 13.40 0.265 .001 log ESR y = 0.179x + 13.16 0.070 .20 RDW With Anemia (n = 220) Parameter Regression Equation r P log CRP y = 0.747x + 14.37 0.214 <.001 log ESR y = 0.093x + 14.68 -0.016 <.001
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|Title Annotation:||Letters to the Editor|
|Author:||Lee, Woong Soo; Kim, Think-You|
|Publication:||Archives of Pathology & Laboratory Medicine|
|Article Type:||Letter to the editor|
|Date:||Apr 1, 2010|
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