Evaluation of serum calprotectin level as a biomarker of disease activity in rheumatoid arthritis and osteoarthritis patients

Background: Rheumatoid Arthritis (RA) is the most common type of chronic inflammatory arthritis with unknown etiology marked by a symmetric, peripheral polyarthritis. Calprotectin also can be used as a biomarker of disease activity in inflammatory arthritis and other autoimmune diseases. Objective: In this study, we evaluated the association between serum calprotectin level and severity of RA activity. Methods: A cross-sectional study was conducted on 44 RA patients with disease flare-up. Serum samples were obtained from all patients to measure calprotectin, ESR, CRP prior to starting the treatment and after treatment period in the remission phase. Based on Disease Activity Score 28 (DAS28), disease activity was calculated. Results: Of 44 RA patients, 9(20.5%) were male and 35(79.5%) were female. The mean age of our cases was 53±1.6 years. Seventeen (38.6%) patients had moderate DAS28 and 27(61.4%) had high DAS28. The average level of calprotectin in the flare-up phase was 347.12±203.60 ng/ml and 188.04±23.58 ng/ml in the remission phase. We did not find any significant association between calprotectin and tender joint count (TJC; P=0.22), swollen joint count (SJC; P=0.87), and general health (GH; P=0.59), whereas significant associations were found between the calprotectin level and ESR (p=0.001) and DAS28 (p=0.02). The average calprotectin level in moderate DAS28 (275.21±217.96 ng/ml) was significantly lower than that in high DAS28 (392.4±183.88 ng/ml) (p=0.05). Conclusion: We showed that the serum level of calprotectin can be a useful and reliable biomarker in RA activity and its severity. It also can predict treatment response.