Familial Mediterranean fever in children and adolescents: factors for colchicine dosage and predicting parameters for dose increase.

ABSTRACT

Objectives: The aim was to analyse factors influencing the individual colchicine dose in children with FMF, to evaluate the impact of dose adjustment on the clinical course and inflammation and to identify clinical parameters and biomarkers that predict dose increase in the near future. Methods: Data from 409 paediatric FMF patients (4566 visits) derived from the national auto-inflammatory diseases registry were analysed. Serum concentrations of S100 molecules were determined by ELISA. Results: The age-dependent colchicine dose is influenced by the present genotype. The body surface area is the anthropometric parameter that correlates best with the applied dosages. Colchicine introduction and dose increase lead to significant reduction of clinical symptoms and inflammation. During established colchicine therapy, an increase of one single biomarker increases the likelihood of a dose increment in the next 12 months with a factor of 1.62-1.94. A combination of biomarkers including S100 molecules increases this odds ratio up to 4.66 when analysing all patients and up to 7.27 when analysing patients with a high risk of severe disease. Conclusion: Colchicine therapy is currently guided mainly by the occurrence of clinical symptoms and serological inflammation. Other factors, such as the genotype, the body surface area and biomarkers, will help to manage colchicine therapy in a more individualized fashion. The additional analysis of S100 molecules as sensitive biomarkers will help to identify patients at risk for dose increases in the near future.