Serum Calprotectin as a Promising Inflammatory Biomarker in Psoriatic Arthritis: a 1-Year Longitudinal Study.

ABSTRACT

INTRODUCTION: There are few biomarkers correlated with psoriatic arthritis (PsA). We aimed to explore the clinical value of calprotectin (CLP) in PsA in disease activity and treatment targets. METHODS: Serum CLP was detected by enzyme-linked immunosorbent assay (ELISA) in 71 patients with PsA, 55 patients with psoriasis (PsO), and 10 healthy controls. The association of serum CLP with disease activity index at baseline and follow-up was analyzed. Cox regression and receiver operating characteristic (ROC) analysis were used to evaluate the potential of CLP for predicting the achievement of treatment targets, including low disease activity (LDA), remission, and minimal disease activity (MDA). RESULTS: Serum CLP levels (µg/ml) were significantly increased in patients with PsA/PsO compared with healthy controls (p < 0.001). Serum CLP levels were positively associated with psoriasis area and severity index (PASI), disease activity in psoriatic arthritis (DAPSA), and its components [including tender joint count (TJC), swollen joint count (SJC), patient's global assessment (PGA), and visual analog scale (VAS)-pain, r 0.290-0.601, all p value < 0.05]. After 1-year follow-up, the number of patients with PsA in remission and MDA increased [17 (23.9%) versus 47 (66.1%) and 21 (29.5%) versus 52 (73.2%) respectively, all p value < 0.001]. Cox regression and Kaplan-Meier survival analysis indicated that patients with lower CLP obtain LDA, MDA, and remission earlier, including remission and MDA within a year (all p-value < 0.05). ROC analysis showed the ability of serum at baseline to predict the achievement of the treatment target in 3 months [area under the curve (AUC) 0.663-0.691, all p-values < 0.05]. CONCLUSIONS: Serum CLP level was correlated with disease activity in PsA. It also possessed the ability to predict the achievement of the therapeutic target. These features of CLP would make it a useful tool in clinical work.

Psoriatic disease is a group of heterogeneous inflammatory conditions, mainly affecting patients' skin and joints. Among the few biomarkers associated with inflammation in psoriatic disease, serum calprotectin may be a promising one. Therefore, we conducted a longitudinal study to explore the clinical significance of calprotectin in patients with psoriatic arthritis at Peking University First Hospital. We found that the level of serum calprotectin positively correlated with disease activity parameters and scores in psoriatic arthritis. It also possessed the ability to predict the achievement of treatment targets, including remission and minimal disease activity. On the basis of the findings of our study, we reckon that CLP may be a useful tool in clinical work.