Approximately half of patients with rheumatoid arthritis (RA) have normal C-reactive protein (CRP) levels. Calprotectin is a promising and likely more specific biomarker of disease activity than conventionally used acute phase reactants. We aimed to analyse the levels of serum calprotectin in RA patients with clinically active disease and with normal/low CRP. A total of 160 RA patients underwent clinical examination (DAS28-ESR and CDAI). The levels of calprotectin were analysed in patients with moderate to high disease activity with normal/low CRP levels and in 32 healthy subjects. The discriminatory capacity of calprotectin to identify clinically active patients in spite of normal/low CRP was assessed using ROC curves. Out of all RA patients, 74/160 (46.3%) were in remission or had low disease activity according to DAS28 and had normal/low CRP levels. However, 51/160 (32%) had normal/low CRP levels despite having moderate to high disease activity. In these patients, calprotectin levels were significantly higher than those in patients who had normal/low CRP and were in remission or showed low disease activity (2.7 ± 1.5 vs. 2.1 ± 1.2 μg/mL, p = 0.043), which differed from those in healthy subjects (2.7 ± 1.5 vs. 1.9 ± 1.2 μg/mL, p = 0.011). The discriminatory capacity for calprotectin to distinguish clinically active vs. inactive disease despite normal/low CRP using AUC of the DAS28 was 0.607 (95% CI 0.503 to 0.711, p = 0.043). The present study demonstrates that calprotectin may reflect inflammatory activity in RA patients where CRP fails to do so.

• Klíčová slova
• C-reactive protein, Calprotectin, Inflammation, Rheumatoid arthritis,
• MeSH
• biologické markery krev   MeSH
• C-reaktivní protein analýza   MeSH
• krevní sedimentace MeSH
• leukocytární L1-antigenní komplex krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• referenční hodnoty MeSH
• revmatoidní artritida krev   MeSH
• stupeň závažnosti nemoci MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Finsko MeSH
• Názvy látek
• biologické markery MeSH
• C-reaktivní protein MeSH
• leukocytární L1-antigenní komplex MeSH

BACKGROUND: Calprotectin may be a sensitive biomarker of rheumatoid arthritis (RA) disease activity. OBJECTIVES: In the current study, we investigated whether calprotectin is a better biomarker than CRP for predicting clinical activity and ultrasound parameters in patients with RA. METHODS: A total of 160 patients with RA underwent clinical (swollen joint count-SJC, tender joint count-TJC, Disease Activity Score-DAS28, Clinical Disease Activity Index-CDAI, and simplified Disease Activity Index-SDAI) and ultrasound (German US7) examination. Clinical and laboratory measures were correlated with ultrasound findings using Spearman´s correlation coefficient. Differences in serum calprotectin levels in patients with variable disease activity according to the DAS28-ESR and CDAI scores were assessed using ANOVA. Multivariate regression analysis was used to determine the predictive values of calprotectin, CRP and SJC for CDAI and PD US synovitis scores. RESULTS: Serum calprotectin was significantly associated with DAS28-ESR (r = 0.321, p<0.001), DAS28-CRP (r = 0.346, p<0.001), SDAI (r = 0.305, p<0.001), CDAI (r = 0.279, p<0.001) scores and CRP levels (r = 0.556, p<0.001). Moreover, calprotectin was significantly correlated with GS (r = 0.379, p<0.001) and PD synovitis scores (r = 0.419, p<0.001). The multivariate regression analysis showed that calprotectin is a better predictor of the CDAI score and PD US synovitis than CRP. CONCLUSIONS: The results of this study support an additional role of calprotectin in assessing inflammatory activity in patients with RA.

• MeSH
• C-reaktivní protein metabolismus   MeSH
• dospělí MeSH
• kohortové studie MeSH
• leukocytární L1-antigenní komplex krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• revmatoidní artritida krev   diagnostické zobrazování   patologie   MeSH
• ultrasonografie MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• C-reaktivní protein MeSH
• leukocytární L1-antigenní komplex MeSH