The cally index as an indicator of inflammatory burden across clinical phases of familial mediterranean fever.

backgroundFamilial Mediterranean fever (FMF) is characterised by recurrent inflammatory episodes and persistent subclinical inflammation, which may lead to long-term consequences such as amyloidosis. Several biomarkers have been identified to assess disease activity. The C-reactive protein-albumin-lymphocyte (CALLY) index is a developing biomarker that combines immunological, nutritional, and inflammatory status. This study aimed to evaluate the clinical usefulness of the CALLY index in distinguishing FMF attacks from attack-free periods.

methodsSeventy healthy controls and 128 FMF patients with a diagnosis based on the Livneh criteria were included. Seventy-one individuals were assessed during the attack-free period, while 57 patients were evaluated during an attack. Clinical characteristics, inflammatory markers, and laboratory data were compared between groups. Multivariate logistic regression analysis was performed to identify independent predictors of FMF attacks. Discriminative performance was evaluated using ROC analysis.

resultsPatients with FMF attacks had statistically significantly lower CALLY index and significantly higher inflammatory marker levels compared to those in the attack-free period and the control group. Attack-free FMF patients had significantly lower CALLY index levels than the control group. The CALLY index was negatively correlated with the neutrophil count, erythrocyte sedimentation rate, and the systemic immune-inflammatory index. A lower level of the CALLY index was an independent predictor for FMF attack according to the multivariate logistic regression analysis (p = 0.005, OR = 0.25). According to ROC analysis, the CALLY index demonstrated outstanding diagnostic accuracy for the diagnosis of FMF attack, with an optimal cut-off value of 0.70 (AUC = 0.931, sensitivity 91.2%, specificity 87.3%).

conclusionThe CALLY index is a simple, cost-effective, and reliable biomarker that represents the inflammatory burden in FMF. Its decrease in both the attack and subclinical stages suggests that it can be used to monitor disease activity and identify individuals who may experience inflammation flares. Key Points • The CALLY index is markedly reduced during familial Mediterranean fever attacks compared with attack-free periods and healthy individuals. • Lower CALLY index values are also observed in attack-free patients, suggesting the presence of persistent subclinical inflammation. • The CALLY index independently predicts FMF attacks and shows high discriminative performance for attack identification. • By integrating inflammatory, immunological, and nutritional parameters, the CALLY index offers a practical tool for monitoring disease activity in FMF.