Performance of the new 'Eurofever/PRINTO classification criteria' in FMF patients.

OBJECTIVE: Recently a new set of criteria proposed for the classification of auto inflammatory recurrent fevers including familial Mediterranean Fever (FMF). We aimed to compare the sensitivity and specificity of the new Eurofever/PRINTO classification criteria with those of the Tel Hashomer and Yalcinkaya-Ozen criteria.

METHODS: 151 consecutive FMF patients between February and May 2019 who were followed at Hacettepe University Department of Pediatric Rheumatology were included in this study. A group of 82 patients with periodic fever 66 periodic fever, aphthosis, pharyngitis and adenitis syndrome (PFAPA), nine cryopyrin-associated periodic syndrome (CAPS) and seven mevalonate kinase deficiency/hyperimmunoglobulin D syndrome (MKD/HIDS) patients) served as controls. GraphPad 6.0 was used for statistical analysis.

RESULTS: Three different classification criteria were analyzed in 151 FMF patients with a median age at diagnosis of 5 years and in 82 controls with a median age at diagnosis of 3 years. The sensitivity of the new Eurofever/PRINTO criteria (96%) was highest (Tel Hashomer criteria-88.4% and Yalcinkaya-Ozen criteria-93.4%). However, the specificity of these criteria (73.1%) was lowest (Tel Hashomer criteria-92.6% and Yalcinkaya-Ozen criteria-84.1%). The new Eurofever/PRINTO criteria achieved the highest sensitivity (100%) in biallelic exon 10 mutation patients (Tel Hashomer criteria-87.4% and Yalcinkaya-Ozen criteria-94.2%). However, the new set had the lowest sensitivity (88.2%) in heterozygote exon 10 mutation patients (Tel Hashomer criteria 94.1% and Yalcinkaya-Ozen criteria 94.1%).

CONCLUSION: In this Turkish cohort, the new Eurofever/PRINTO criteria have a better sensitivity but lower specificity with higher misclassifications than other two well-known criteria. The combination of clinical manifestations with genotype increased the sensitivity. The lower specificity may be due to the high carrier rate in our population. Although the ethnicity information lowers the specificity, 'clinical-only' criteria set may still guide the clinician to perform appropriate genetic testing in patients with recurrent fever.