Serum cystatin C as a marker of renal dysfunction in children with juvenile idiopathic arthritis

Abstract

An accurate assessment of the estimated glomerular filtration rate (eGFR) is important for early detection of chronic kidney disease, control of nephrotoxicity, and dose adjustment of drugs. To date, there has been only one cohort retrospective study of the prevalence of chronic kidney disease in children with juvenile idiopathic arthritis (JIA). Purpose - to determine the level of serum cystatin C and, on its basis, the state of eGFR depending on the form of the clinical course, degree of activity, methods of treatment of JIA in children. Materials and methods. 80 children with JIA were examined. The content of serum cystatin C was determined by enzyme-linked immunosorbent assay. The Hoek formula was used to calculate eGFR based on the level of cystatin C in blood serum. Results. A decrease in eGFR below 90 ml/min/1.73m2 to 63.08 ml/min/1.73m2 based on serum cystatin C was found in 41.3% of children with JIA. The variant of the clinical course of JIA does not affect the concentration of serum cystatin С and the level of eGFR. Meanwhile, a high degree of risk of developing a decrease in eGFR in children with polyarthritis was established - 72.7% versus 48.9% (OR=2.78; CI: 1.07-7.24; p<0.04). Elevated serum cystatin С levels and decreased eGFR are associated with the degree of JIA activity and its duration. A decrease in eGFR is observed in all children with high activity of JIA, 71.4% - with low activity, 28.3% - in remission. A low risk of developing a decrease in eGFR in children in remission of JIA was established - 51.5% versus 91.5% (OR=0.10; CI: 0.03-0.34; p<0.001). The duration of the active stage of JIA ≥4 years negatively affects the level of eGFR, which leads to a high risk of developing a decrease in eGFR - 39.4% versus 17% (OR=3.17; CI: 1.13-8.9; p<0.04). A high risk of developing a decrease in eGFR was established in children with JIA who received non-steroidal anti-inflammatory drugs (NSAIDs) at the time of the examination - 54.5% versus 8.5% (OR=12.9; CI: 3.76-44.25; p<0.001). The use of immunobiological therapy is associated with a low risk of developing a decrease in eGFR - 9.1% versus 46.8% (OR=0.11; CI: 0.03-0.42; p<0.001). Conclusions. Renal dysfunction was found in 41.3% of children with JIA. Its development is affected by high activity of JIA, duration of the active stage of JIA ≥4 years, and treatment with NSAIDs. The study was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the institution specified in the work. Informed consent was obtained from the parents of the children for the research. No conflict of interests was declared by the authors. Key words: juvenile idiopathic arthritis, renal dysfunction.