Blood calprotectin in children with juvenile idiopathic arthritis: relationship to flare development after discontinuation of treatment

Objectives: The study aim was to prospectively evaluate the relationship between disease flare development in children with juvenile idiopathic arthritis (JIA) after discontinuation of treatment and serum calprotectin levels (MRP8/14).

Material and methods: Determination of blood serum level of calprotectin was performed in 54 patients with inactive JIA from various regions of Ukraine. The inclusion criterion was the existence of an inactive state of the disease in children with JIA for at least 6 months. During 1 week after blood sampling for determination of serum calprotectin (MRP8/14) level the patients were completely discontinued of all therapy. Determination of calprotectin level in blood serum was performed with reagents EK-MRP8/14 Buhlmann (MRP8/14; S100A8/9), Switzerland, using the ELISA method.

Results: The trial results showed that 3 months after discontinuation of treatment in patients with inactive JIA, the flares developed in 5 out of 54 patients (9.3%). The median calprotectin level before discontinuation of the treatment was 1,700 ng/ml in patients who developed a flare, and 1,500 ng/ml in other studied patients (not statistically significant). At 6 months, the flare had developed in an additional 3 out of 48 (6.3%) of patients, who continued to be followed up, while their median calprotectin serum levels were 1,300 ng/ml and 1,500 ng/ml respectively (not statistically significant). At 12 months, the flares had developed in 13 more out of 45 (28.9%) patients, who continued to be followed up, while the median calprotectin serum level in these patients before discontinuation of treatment was 1,100 ng/ml and 1,650 ng/ml respectively (not statistically significant).

Conclusion: After discontinuation of treatment a flare over the next year of follow-up developed in 38.9% of patients. The study results did not reveal a significant difference in calprotectin level in patients with JIA prior to complete discontinuation of treatment who developed a flare and those without a flare after 3, 6 and 12 months.