The frequency of juvenile spondyloarthropathies in childhood familial Mediterranean fever

Objective. The aim of this study is to evaluate the frequency of juvenile spondyloarthropathies (JSpA) in childhood familial Mediterranean fever (FMF) patients from a single tertiary centre. Additionally, we aimed to investigate the main clinical characteristics of FMF patients with coexistence of JSpA clinical features. Methods. We evaluated 323 paediatric FMF patients who were followed at our clinic. All of the patients were evaluated by three different investigators (EO, DS, ET) for the presence of JSpA clinical signs, according to the recently proposed JSpA criteria. Patients preliminary diagnosed as FMF+ JSpA were further evaluated by the experienced paediatric rheumatologist (OK) who made the final decision on the diagnosis of the patients. Results. The female/male ratio was 1.13 (n= 172/151). Preliminarily, 33 (10.2%) out of 323 paediatric FMF patients had been classified as FMF+ JSpA. An experienced paediatric rheumatologist re-evaluated the classified patients and all of them were diagnosed as definitive FMF+ JSpA. The M694V mutation was the most common mutation, seen in (n= 18/32) (56.3%) FMF+ JSpA and in (n= 152/251) (61.1%) FMF patients without JSpA/JIA. Conclusion. Apart from acute monoarthritis of the lower extremities, the chronic arthritis should be kept on mind among FMF patients with articular involvement. The JSpA should be considered in FMF patients with oligoarthritis, inflammatory back pain and enthesopathy complaints with onset over 6 years. Newly proposed JSpA criteria can be used to spondyloarthropathies in childhood FMF.