Abstract
Familial Mediterranean fever (FMF) is characterized by recurrent episodes of fever and serositis. Blood-based biomarkers determined in FMF patients during attack-free periods could be used to predict the risk of amyloidosis and the severity of the disease. The recently defined pan-immune-inflammation value (PIV) comprises four distinct subsets of blood cells and serves as an easily accessible and cost-effective marker. The objective of this study was to assess the role of PIV in predicting amyloidosis and moderate-to-severe disease. Clinical characteristics and laboratory values during the attack-free period were retrospectively analyzed in 321 patients over 18 years of age diagnosed with familial Mediterranean fever (FMF). In our tertiary adult rheumatology outpatient clinic, disease severity and laboratory markers were evaluated during the first attack-free interval. At baseline, patients with amyloidosis were excluded. Patients were categorized based on the presence of amyloidosis and the severity of the disease. When focusing on amyloidosis in receiver operating characteristic (ROC) analysis, optimal cut-off values for pan-immune-inflammation value (PIV), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio were determined as ≥518.1, ≥2.3, and ≥127.2, respectively. In multivariate analysis, PIV, C-reactive protein (CRP), and the presence of the M694V homozygous mutation emerged as independent risk factors for both amyloidosis and moderate-to-severe disease. Additionally, NLR was identified as an independent risk factor for amyloidosis, while red blood cell distribution width was associated with moderate-to-severe disease. In patients with FMF, especially in the presence of the M694V homozygous mutation, CRP and PIV may be useful in predicting both amyloidosis and moderate-to-severe disease.