Evaluation of subclinical inflammation in familial Mediterranean fever patients: relations with mutation types and attack status: a retrospective study

Familial Mediterranean fever (FMF) is an autosomal recessive autoinflammatory disease of childhood and adulthood. Development of systemic amyloidosis and frequent attack influence quality of life and survival. There is sporadic evidence indicating subclinical inflammation in patients with FMF. We aimed to assess subclinical inflammation using neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and C-reactive protein (CRP) in pediatric patients with FMF in the attack-free period. In this retrospective study, we reviewed the files of all FMF patients in our pediatric rheumatology outpatient clinic in a tertiary center and enrolled those with sufficient clinical and laboratory data. We also enrolled 73 controls. We grouped the patients according to being in attack period or attack-free period. We compared CRP, NLR, PLR, and WBC (white blood cell) levels between different mutations and polymorphisms. We also compared patients in the attack period with those in attack-free period. We enrolled 61 patients in attack period, 509 patients in attack-free period, and 73 controls. There was no difference between patients with different mutations with respect to NLR or PLR levels in the attack-free period. However, CRP levels were higher in patients with homozygous exon 10 mutations, especially those with homozygous M694V mutations compared with other mutations. However, CRP levels were mostly normal in these patients. Our data are against the reported fact that patients with FMF have higher NLR or PLR levels in attack-free periods. However, CRP levels were higher in the presence of homozygous exon 10 mutations (in particular homozygous M694V mutations).