Mediterr J Rheumatol 2021;32(1):56-65
Serum Calprotectin is Indicating Clinical and Ultrasonographic Disease Activity in Rheumatoid Arthritis, even with Normal C-Reactive Protein Levels
Authors Information

1Division of Rheumatology, Department of Internal Medicine, and 2Department of Medical Microbiology, Ankara University Faculty of Medicine, Ankara, Turkey

Murat Torgutalp, Mucteba Enes Yayla, Didem Şahin Eroğlu, Ayse Bahar Kelesoglu Dincer, Emine Uslu Yurteri, Ilyas Ercan Okatan, Serdar Sezer, Emine Gozde Aydemir Guloksuz, Ebru Us, Tahsin Murat Turgay, Gulay Kınıklı, Askın Ates  


Objective: Calprotectin is an inflammatory biomarker to assess disease activity in rheumatoid arthritis (RA). The objective of this study was to test whether serum calprotectin is associated with clinical and ultrasonographic disease activity in patients with RA and to analyze its predicting value for disease activity evaluation despite normal C-Reactive protein (CRP) levels. Methods: We included 80 patients with RA and 30 healthy subjects. Patients were examined clinically and by ultrasound (US7 score) along with laboratory parameters (calprotectin, CRP, erythrocyte sedimentation rate (ESR)). Disease activity scores (DAS28) were calculated to assess disease activity. Firstly, patients were divided into four subgroups according to the DAS28-ESR (high, moderate, low disease activity, and remission), then into two subgroups; group-1 (DAS-28≤3.2), group-2 (DAS28>3.2). The predicting value of calprotectin for disease activity in patients with normal CRP was analyzed with univariate and multivariate analysis and receiver operating characteristic curves. Results: Calprotectin levels were higher in RA patients than controls (96.3±45.9 ng/ml, 54.7±50.0 ng/ml, respectively; p<0.001). Calprotectin levels were 74.8±45.5 ng/ml in group-1 (n=37) and 114.7±37.9 ng/ml in group-2 (n=43) (p<0.001). In univariate analyses, calprotectin was significantly correlated with clinical, laboratory, and ultrasound parameters (p<0.05), and was a better predictor of power doppler synovitis than CRP in multivariate analysis (OR=1.014; 95%CI 1.002-1.027; p=0.024). The discriminatory capacity for calprotectin to distinguish ultrasonographically active disease in patients with normal CRP levels using AUC was 0.75 (95%CI 0.56-0.90, p=0.023). Conclusions: Calprotectin represents disease activity, even in patients who are clinical and ultrasonographical active but have normal CRP levels.

Article Submitted: 15 May 2020; Revised Form: 28 Sep 2020; Article Accepted: 13 Oct 2020; Available Online: 15 Feb 2021


This work is licensed under a Creative Commons Attribution 4.0 International License (CC-BY). 

©Torgutalp M, Yayla ME, Eroglu DS, Kelesoglu Dincer AB, Yurteri EU, Okatan IE, Sezer S, Aydemir Guloksuz EG, Us E, Turgay TM, Kinikli G, Ates A.