Background Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are common laboratory measurements of systemic inflammation in clinical practice of rheumatoid arthritis (RA). Although two measures well correlate with each other, they depend on different pathophysiologic mechanisms and sometimes show discordant values. However, there is controversy over interpretation and sensitivity of CRP and ESR as guidance for inflammation [1,2].
Objectives To identify factors that associate with the discordance between ESR and CRP.
Methods All patients with RA followed in our institution on regular basis were cross-sectionally reviewed. Clinical variables including ESR, CRP, clinical disease activity index (CDAI), metallomatrixprotease (MMP)-3, heamglobin, immunogloblin, rheumatoid factor (RF) were obtained. The upper limits of normal rage for ESR and CRP in our institution are 10 mm/h for male and 15 for female and 0.35 mg /dL, respectively. Patients were divided in 4 groups depending on each measures as follows: CRP/ESR high (CE-high), CRP/ESR normal (CE-normal), CRP high ESR normal (C-high), ESR high CRP normal (E-high).
Results Baseline characteristics of 1,474 patients are as follows: mean age was 62 years, 1,253 (85%) were female, mean disease duration was 11.9 years, mean ESR was 20.1 mm/h, mean CRP was 0.26 mg/dL, positivity of RF was 85% and mean DAS28 was 2.4. Treatments for RA were as follows, disease modifying arnti-rheumatic drugs including methotrexate 89%, biologic agents 54%, and prednisolone 19%. The values of ESR and CRP were generally well correlated (R =0.62, P=0.00). When patients were categorized depending on ESR and CRP, 763 patients (51.8%) were in CE-normal, 35 (2.4%) in C-high, 447 (30.3%) in E-high and 229 (15.5%) CE-high. CDAI was the lowest in CE-normal (3.9), and E-high, C-high and CE-high were 4.2, 4.7, and 4.8 respectively P=0.3). Comparing the C-high and E-high group, C-high was younger (57 vs 65 yo, P=0.009), used higher dose of prednisolone (4.1 vs 2.1 mg/day, P=0.001) with lower DAS28-ESR (2.3 vs 2.8, P=0.00), and higher MMP-3 (113 vs 67 mg/dL, P=0.03). Additionally, C-high had lower IgG (1,165 vs 1,505 mg/dL, P=0.00) and lower RF (63 vs 111, P=0.02).
Conclusions The discordance between CRP and ESR was observed in approximately one-third of the patients with RA in clinical practice. Although both contribute to disease activity index in a similar degree, CRP is a better measure for inflammation while ESR tends to reflect immunological disorder.
Walsh L, et al. Ann Rheum Dis. 1979;38:362-363
Kay J, et al. Arthritis Res Therapy 2014. 16:R40
Disclosure of Interest Y. Kaneko Consultant for: Abbvie, Paid instructor for: Eisai Pharmaceutical, Chugai Pharmaceutical, Astellas Pharmaceutical, Mitsubishi Tanabe Pharma Corporation, Pfizer, Speakers bureau: Abbvie, Eisai Pharmaceutical, Chugai Pharmaceutical, Bristol Myers Squibb, Astellas Pharmaceutical, Mitsubishi Tanabe Pharma Corporation, Pfizer, Janssen, UCB, H. Kondo: None declared, M. Ohta: None declared, T. Takeuchi Grant/research support from: Astellas Pharma, Bristol–Myers K.K., Chugai Pharmaceutical Co, Ltd., Daiichi Sankyo Co., Ltd., Eisai Co., Ltd., Mitsubishi Tanabe Pharma Co., Pfizer Japan Inc., Santen Pharmaceutical Co., Ltd., Takeda Pharmaceutical Co., Ltd., Teijin Pharma Ltd., AbbVie GK, Asahikasei Pharma Corp., and Taisho Toyama Pharmaceutical Co., Ltd.,SymBio Pharmaceuticals Ltd., Consultant for: Astra Zeneca K.K., Eli Lilly Japan K.K., Novartis Pharma K.K., Mitsubishi Tanabe Pharma Co., and Asahi Kasei Medical K.K.,abbivie GK, Daiichi Sankyo Co.,Ltd., Bristol–Myers K.K., Nipponkayaku Co.Ltd., Paid instructor for: Mitsubishi Tanabe Pharma Co., Eisai Co., Ltd., Abbivie GK, Speakers bureau: AbbVie GK., Bristol–Myers K.K., Chugai Pharmaceutical Co,. Ltd., Eisai Co., Ltd., Janssen Pharmaceutical K.K., Mitsubishi Tanabe Pharma Co., Pfizer Japan Inc., and Takeda Pharmaceutical Co., Ltd., Astellas Pharma, and Diaichi Sankyo Co.,Ltd., Celtrion, Nipponkayaku Co.Ltd